But I need to use some Android Apps on my tablet in the Spacedesk viewer. The problem is that I don’t know how to open Android App in the Spacedesk viewer.
This is not possible. spacedesk Viewer app don’t have access to any third party applications installed on your android tablet.
spacedesk Viewer app only receives Desktop screen update from your server primary machine and sends back remote input(e.g. touch, keyboard) to server primary machine over your local area network.