Hi @Screng and welcome to the forums.
Firstly, Astral is graphics intensive. It will chew up large amounts of graphics memory and power. As such it is designed to work on desktop machines.
Secondly, Astral has tools that work on mobile devices. The initiative tracker, the audio player, and Chat can be used on mobiles.
That all said, some people have been able to play on Astral using older mobile phones. The performance isn’t brilliant, but it can work.
The real issues are the size of the maps used in the game, and the complexity of the character sheets.
The team work hard on improving performance so that you can use mobile devices, but Astral does use WebGL, which is the 3D browser engine, for all its graphics, so experience may vary.
Worth pointing out, since the guy has an Apple device, Astral does not work properly, at all, on the Safari browser, so the first step would be to install Google Chrome or Microsoft Edge on the device before even trying to get a game on Astral to run on the iPad.
Most of Astral will allow you to only use left clicks. Right clicks are reserved for context menus which do help speed up game play, but all those features can be accessed through the Player Menu (Player’s icon in the bottom left corner.
One thing that you will not be able to do is use a mobile device to GM a game. You just will not have enough screen to display everything comfortably.
Hope this helps, and feel free to reach out either here or on Astral’s Discord server if you have any other questions.