Two different meanings of download
An application package installs software; an offline film stores video through a supported viewing application. My List is a third thing: it keeps the production you want to revisit.
Prepare the actual viewing copy
Inspect the selected application’s offline option for the exact film or episode. Complete any offered download while connected, then check the audio and captions without a network.
When the title is available only online
A working online offer does not imply an offline download is included. Keep a second choice ready if you are preparing entertainment for travel. The catalogue does not provide a separate archive of movie files.
A missing download button
Look in the application supplying the video, not the saved-title control here. A device, account or title restriction can change which offline options appear. Use that application’s own explanation for its current rules.