Hello @space_cool welcome to Zwift forums.
You may have to give the Zwift app permission to access the Bluetooth hardware on your Android device.
When you ran the Zwift app for the first time, the app should have asked you for permissions to access the Locations folder. In Android, Bluetooth permissions are buried under the Location permission (it’s not obvious, but that’s the reason).
If you denied permission to the Location folder, you can allow permissions for the Zwift app. How-to has been discussed here. If you’re running the newest version of Android, it’s buried under two levels of folders.
Alternately - you can uninstall the Zwift app, then reinstall, and give permissions the next time.