By all accounts, Microsoft isn't letting you activate Windows from your phone anymore, so make sure you have an internet connection.
You can now use up to 90% of the desktop screen space when streaming Android apps to Windows 11 using the Microsoft Phone Link app.
The official Microsoft shortcut to connect your Android and iPhone to a Windows 10/11 PC. Sends users to the Phone Link app to set up and pair. Facilitates the synchronisation of messages, ...