If a user is behind an authentication proxy, the user provides the proxy credentials in the Creative Cloud App. On launching an Adobe application, a display box is displayed prompting the user to enter the proxy credentials (for authorization and licensing related calls) again. This happens although the user has provided them earlier.
Try removing App Store cache folders from your User’s Library’s Cache; Update your combo macOS download instead of app store update. Remember, the most common reason why the App Store is not working on your Mac Catalina is mostly because of poor Wi-Fi connection, different Apple Id, proxy setup in-network, VPN setup or the Apple system is down.
Macos Show Desktop
Macos Proxy Tool
Provide credentials again and select Save in Keychain control.
Macos Proxy Bypass
Once the credentials are entered in the app and the user opts for remembering the credentials, it should not display a dialog box prompting to enter the proxy credentials again.