If Office keeps asking you to sign in, the problem might be your email profile.
Open Outlook and go to File > Account Settings > Manage Profiles.
Now you need to select Show Profiles.
Select your profile and click the Remove button.
After doing that, you just need to create a new Outlook profile.
Open Outlook. Now go to File > Account Settings > Manage Profiles > Show Profiles > Add.
Enter the desired profile name and click OK. Now follow the instructions on the screen to complete the account creation process.
Once you create a new account, check if the problem is still there