Help, I've installed the app but don't see the actions in Shortcuts
Short answer: restart/reboot the device. If you still don't see them, uninstall and reinstall the app.
When an app containing Shortcuts actions is installed, the operating system should automatically register them with Shortcuts, but sometimes it just doesn't. I'm certain that's a bug in iOS/macOS.
Unfortunately, apps can't explicitly instruct the system to add actions to Shortcuts. But since it's impossible to force the OS to look again, the first option is restarting the device.
If that doesn't do the trick, please uninstall the app and reinstall it again. So far, in most reported cases this solved the problem, and the actions appeared in Shortcuts.