How to Log Into Your Microsoft 365 Account for the First Time and Set Up MFA (Microsoft Authenticator)
Summary
This guide walks a new Microsoft 365 user through signing in for the first time and completing Multi-Factor Authentication (MFA) setup using the Microsoft Authenticator app. You’ll confirm your password works, enroll Authenticator, and verify you can sign in successfully afterward.
Assumptions
You have been assigned a Microsoft 365 account in your organization’s tenant.
You received a username (often your work email) and a temporary password or instructions to set a password.
You have access to the device where you will install Microsoft Authenticator (iOS/Android).
Your organization requires MFA and allows Microsoft Authenticator.
You can receive a QR code on-screen (computer or another device) during setup.
You have an internet connection on both your phone and the device you’re signing in on.
Quick Guide
Install Microsoft Authenticator on your phone.
On a computer, go to Microsoft 365 sign-in and sign in with your new account.
When prompted, choose Microsoft Authenticator and start setup.
In Authenticator, add a Work or school account and scan the QR code.
Approve the test notification or enter the code to finish.
Sign out and sign back in once to confirm MFA works.
Step-by-Step Instructions
1) Install Microsoft Authenticator on your phone
On your phone, open the App Store (iPhone) or Google Play Store (Android).
Search for Microsoft Authenticator.
Install the app.
Open the app and allow notifications (recommended so you can approve sign-in prompts).
2) Sign in to Microsoft 365 for the first time
On your computer (recommended), open a browser window in InPrivate/Incognito mode (optional but helpful).
Go to your organization’s Microsoft 365 sign-in page (commonly the Microsoft 365 portal or a provided sign-in link).
Enter your work email/username and click Next.
Enter your temporary password (or your new password if you already set it).
If prompted, create a new password:
Enter the temporary password once.
Create and confirm a new password that meets your organization’s requirements.
Continue until you see the security/MFA setup prompt.
3) Start MFA setup with Microsoft Authenticator
When you see a prompt like “More information required” or “Set up your account”, select Next.
If asked to choose an authentication method, select Microsoft Authenticator.
Choose the option to set up or add the Authenticator app.
4) Add your work account to Authenticator and scan the QR code
On your phone, open Microsoft Authenticator.
Tap Add account (often a “+” icon).
Select Work or school account.
Choose Scan QR code.
On your computer, a QR code should be displayed during setup.
Use your phone to scan the QR code on the screen.
5) Complete verification (test prompt)
After scanning, your computer will typically ask you to approve a notification or complete a test.
On your phone, approve the sign-in prompt in Authenticator.
If you receive a number-matching prompt:
Confirm the number shown on your computer matches what Authenticator asks for.
Approve the request.
Wait for the confirmation message that MFA setup is complete.
6) Confirm you can sign in successfully
Sign out of Microsoft 365.
Close the browser tab(s).
Open a new browser window and sign in again.
When prompted, approve the sign-in request in Microsoft Authenticator.
Confirm you reach the Microsoft 365 landing page or your requested app (Outlook, Teams, etc.).
Troubleshooting
I didn’t get an MFA prompt on my phone
Confirm your phone has internet access (Wi-Fi or cellular).
In Authenticator, ensure Notifications are enabled for the app.
Open the Authenticator app manually and wait a few seconds.
Try signing in again—some prompts expire quickly.
The QR code won’t scan
Increase screen brightness on the device showing the QR code.
Clean your phone camera lens.
Move the phone closer/farther away until the QR code is in focus.
If available, choose an option like “Can’t scan image?” to use a manual method.
I’m stuck on “More information required” every time
You may not have completed the final verification step.
Try signing in again and finish the Authenticator setup flow.
If it loops, clear browser cookies/cache or use an Incognito/InPrivate window.
Authenticator shows the wrong account or multiple accounts
Make sure you added a Work or school account, not a personal Microsoft account.
Verify the account in Authenticator matches your work email/username.
I changed phones / reinstalled the app and now I can’t sign in
MFA is tied to the device/app enrollment. You’ll likely need MFA reset or re-registration by IT.
When to Contact IT Support
Contact IT Support if:
You never received your username or temporary password.
Your account says it doesn’t exist, is blocked, or you receive repeated “incorrect password” errors.
MFA enrollment fails repeatedly (QR code never works, prompts never arrive after troubleshooting).
You replaced your phone or lost access to Authenticator and can’t complete MFA.
You are prompted for a method you are not allowed to use (or Authenticator isn’t available).
About MET Florida
MET Florida supports business IT environments including Microsoft 365 identity access, authentication, and sign-in troubleshooting. We can help confirm your account is provisioned correctly, resolve first-login issues, and assist with MFA enrollment or resets when needed.
MET Florida delivers comprehensive Managed IT Services that function as your outsourced IT department without the overhead of maintaining internal staff. We provide proactive monitoring, responsive help desk support, cybersecurity oversight, and long-term technology planning to keep your business systems stable and secure. Our team works behind the scenes to prevent downtime, resolve issues quickly, and align your technology with your operational goals so your organization can operate with confidence.
