ive been having this for 2-3 months now all i get is the same error after receiving the TestFlight invite, i get the Code, redem the code, App shows up, but when i try to install it, i get ERROR message. ( Could Not in Stall APP NAME. The Request App is Not Avalible or Doesn't Exist.) Even though it an new APP i just created. i have like 25 Apps with install next to the APP Name and each app Gives me the Same Error Message. I think Apple/TestFlight needs to Address this issue. this happens on my Iphone and Tablet.