You can simply send them the prototype link, which they can open with a browser and view it on whatever device you want to. It doesn't have to be through the Adobe app.
You can add "?fullscreen" behind the link, to hide the interface around the prototype and make it fullscreen when they open it.
There are some services out there that "turn websites into apps", which basically open the website through a browser that doesn't have an interface, so the website looks like an app on your phone. They might be able to work with your prototype link to simulate the experience, but it will take some trial and error to see whether it's worth it.