Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello Jesse,
Welcome to Microsoft Community.
I understand your Office 365 works fine using Mobile device , however you cannot access this using your Desktop
I will be guiding through some possible causes and solutions
1 Network Connectivity issues
Firewalls, proxies, or VPNs could be blocking the authentication endpoints. Ensure that your network settings allow access to Office 365 services
2 Incorrect Credentials
Ensure that your username and password are typed correctly. Sometimes, simple typos can prevent successful login
3 Multi factor authenticator
If your organization uses MFA or conditional access policies, ensure that your desktop device meets these requirements
4 Installation
Sometimes, a corrupted installation or having multiple versions of Office can cause issues. Consider reinstalling Office 365 on your desktop
Best Regards,
Sunday | Microsoft Community Support Specialist