How to Sync SharePoint Library to your computer:
Make sure synchronization is enabled at the site level:
Go to site settings.
Go to search -> search and offline availability
Select YES for option: Offline Client Availability
The user should have a least Read permission into the SharePoint library.
1. Open the library you want to sync
2. Click the Sync Button
If you don’t see a Sync button, select the Library tab and then select Sync in the Connect & Export group
In the pop-up window, click Sync Now.
In the pop-up window, click Open Microsoft OneDrive
Click Sync Now in the wizard to start syncing
Once the synchronization is complete, click the Show my files button
You can see the files in your local drive in the SharePoint folder (C:\Users\<<user name>>\SharePoint\SupportTeam – Documents).