how to transfer a movie from my macbook pro to ipad pro

macOS Catalina replaced the iTunes app with a number of other apps. You would access movies or TV episodes from the TV app on your Mac. Accessing either of these from your iPad would require that you log in with the same Apple ID that you purchased these movies with as they are all stored on Apple servers in the Cloud.

Your previous iTunes movie purchases would be available directly from Apple. You should be able to access those if you use the same Apple ID, you purchased them with, on your iPad.