Hi @NKO
Welcome to the Q&A forum.
It seems that you cannot sign into Office apps successfully, could you please log in to office.com for a check?
Which type of account you are using, personally account or organizational account?
If there is no problem logging in to the link above, I suggest you can delete Office related cache files:
Open Finder.
- Press Command + Shift + G, then type
~/Library/Containers/com.microsoft.office
, and then press Enter. - Delete the contents of the folders related to Microsoft 365 (be careful not to delete other important files).
Besides, clear your credentials:
- Open Keychain Access.
- Search for any entries related to Microsoft Office and delete them.
- Restart your computer and try to sign in again.
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