This content can’t be played on this Apple TV

I am trying to access movies (from my imac mini )that I have purchased from apple and it should link to my computer on my Apple TV ….. yet it keeps coming up with “this content can’t be played on this Apple TV “ ……. I have lots and lots of apple products ……I have spent thousands of pounds and would continue too my i moves account has thousands of pounds of movies that I have brought ! And yet it’s not letting me play that content .

I am getting sooooooo tired of apple products failing to do the simplest of tasks……..tasks that use to be easy and standard a few years ago …… and now there’s more and more failures ……is this the start of apple’s unreliability ?? ………I have removed HDMI cables …..I I have reset both Apple TV my iMac …..my router ……my brain …..even turned them all on and off again ! ….please someone help me .