Office 365 apps published from Windows Server 2019 hosts can't be activated as the popup window prompting for password isn't displayed:
Parallels RAS Engineering is aware of this issue and is working on the fix together with Microsoft.
There are two possible workarounds:
- Enable option Use RemoteApp if available as described here. Please take into account that it will resolve the issue only for users running Parallels Client for Windows;
- Publish a desktop from the same host, so users will be able to activate Office 365 when they start the apps in the full desktop session.