Hello, i have this problem, i have installed minecraft, and the twitch apps says thats i dont have it, i click on install and it just go back to the same windows that its says that i dont have installed the game, ill put a gif of the problem and a image that i have ineed installed the game
Twitch didn't seem to register my copy of minecraft as installed. So I had to have a second copy installed on my PC through twitch to count. Not sure if that is what going on with you or might be the admin thing. The end result for me was I have a copy of minecraft vanlia on my PC and then another whole copy installed by twitch. Both use my same login details, I didn't have to buy another copy if you were worried.