Already join the group, but link for app not availabe

[Qushairi Radzuan]

Hi admin, i already join your group hopefully to enjoy Apple Music natively in my Nvidia Shield, but the apps link not working anymore, 

it says " App not availableA testing version of this app hasn't been published yet or isn't available for this account."

hopefully you can fix it, very urge to listen lossless apple music on my soundbar, thanks