Use GIFs in props
When adding GIFs to your props, you can't expect the game your prop will end up in to have the same version of the GIF Player in the same location as you, so you should include the GIF Player (module) in your prop folder instead. You also can't expect the prop to always end up in Workspace, so you should edit your Screens setting to use relative paths.
This tutorial will help you get through both of these steps. We will assume your game currently looks like this:
The AVeryImportantProp folder contains your prop, but the GIF Player is in the place where you put it normally, instead of where it should be to function in a prop. We uploaded this game here, so you can edit it (press ... -> Edit in Studio) and follow along.