You can sync up to 20,000 items total across all synchronized libraries
You can sync up to 5,000 items in a SharePoint library
In SharePoint Online, file names can have up to 256 characters.
Folder names can have up to 250 characters.
Folder name and file name combinations can have up to 250 characters.
1. Open an Office application (i.e. Word, Excel, etc)
2. Click FILE then Account
3. At the right-hand panel click Update Options (beside Office Updates)
4. If updates are disabled, enable it by clicking Enable Updates
5. Click Update Options again then click Update Now
6. Reboot PC once update is done