If the App Store freezes or refuses to download, go to Apple’s official support download page:
Before upgrading, go to Apple Menu > About This Mac > System Report > Software > Applications . Look for the "64-bit" column. If it says "No," that app will be deleted or stop working immediately after the upgrade (Adobe CS6, older Microsoft Office, many classic games). how to update macos high sierra 10.13.6 to 10.15