Question about storage

I’m completely new to this, so forgive if I sound like completely illiterate.

I downloaded Kodi on my firestick, signed up for an RD account, and added umbrella, shadow and Asgard.

My question is once I stream a movie, is that movie saved somewhere on the firestick or on Kodi? Example: my girlfriend and I watched Everything Everywhere All at Once, Angels in the Outfield and Super Mario Bros movie. Once we finished the movies, do I need to go somewhere and delete it or anything? If so, where do I go exactly? I have noticed that the download of the movie is taking much longer than when I downloaded the first movie we watched.