Users on unmanaged or "untrusted" devices will be able to read files in the browser but will be blocked from downloading, printing, or syncing. Disable the "Sync" Button
In the SharePoint Admin Center, set the site to "Allow limited, web-only access." prevent download of files in sharepoint
Preventing users from downloading files in SharePoint is a common requirement for organizations handling sensitive data, intellectual property, or regulated content. While SharePoint is designed for collaboration, you can implement several layers of security to restrict local saving while still allowing users to view and edit documents online. Users on unmanaged or "untrusted" devices will be
By default, SharePoint "Read" permissions allow downloading. To stop this, you must create a custom permission level that removes the "Open Items" permission, which forces the file to stay within the browser. Go to > Site Permissions . Click on Permission Levels . Click on the existing Read permission level. Scroll to the bottom and click Copy Permission Level . Name it "View Only - No Download." Uncheck the box for Open Items (under List Permissions). Note: This automatically unchecks "View Source." Click Create . By default, SharePoint "Read" permissions allow downloading