Hello, thank you for reaching out to Microsoft Q&A.
I understand you're having trouble logging into your Outlook account on your Mac Air.
Based on your description, it seems you're able to log in to Outlook mobile, but not on your laptop, which suggests a connectivity issue.
- Are you using your mobile data network to access Outlook on your mobile?
- Could you please try switching your Mac to a mobile hotspot network and see if you can log in to Outlook that way?
Please note that Support for legacy Outlook for Mac will end in October 2025. Most users have already moved to the new version of Outlook.
To switch to New Outlook, check if your Outlook app has a toggle to turn off Legacy Outlook. If the toggle is not available, you can download the new version from the App Store.
https://apps.apple.com/us/app/microsoft-outlook/id951937596
To troubleshoot, uninstall the older (Legacy) version of Outlook from your device, then install the latest version from the App Store. After installing, try signing in while connected to a different Wi-Fi network to check if you’re able to log in.
Reference:
End of support for legacy Outlook for Mac
Let me know if you still need more help.