Hello Ella,
You cannot directly sync shared files or folders to your PC in File Explorer unless they are added as a shortcut to your own OneDrive.
Go to OneDrive on the web > Shared section.
Right-click the shared folder and select "Remove from My Files".
In the Shared section, right-click the folder and select "Add shortcut to My Files."
Open File Explorer and find your OneDrive folder. In onedrive application.
Right-click the OneDrive cloud icon in the system tray > Settings.
Go to Account > Choose folders and ensure the shared folder is checked
If the folder doesn’t appear, go to Settings > Account > Unlink this PC.
Sign in again to refresh the sync.
After these steps, the shared folder should be available in File Explorer under your OneDrive.
please check this if helps.