do you find it how to open?
yes I did. First try opening the game (It should give you the warning) press done (the lower button. I’m German so I don’t know what it said on in in English) then you have to go to settings -> Privacy & Security-> scroll down then you should see an area that says something along the lines of an unknown app and there should be a button unlock/ use it. Then you just have to either use your password or fingerprint to authorise the app to be started. Hope it helps
this is the link to the apple help site. If it’s in German then I apologise I tried searching in English but the site automatically switched to German.