I purchased a tv series season and it isn't showing up on Apple tv - how long does it take to download?

Welcome to the Apple Community.

Where did you purchase it from and where are you looking on the Apple TV.

Did you get any acknowledgement of purchase, you should get an acknowledgement then a note to say it will be available shortly (depending on connection) a few seconds later you will be told it is ready to play and ask you whether you wish to watch it now or later.

Assuming it has been purchased, select the content which is causing a problem and use the 'Report a problem' button in Your Purchase History.