Here's a link to a review of the Samsung T5 SSD that indicates it is formatted for exFAT and is compatible with the Mac operating system.
Samsung Portable SSD T5 Review & Rating | PCMag.com
iMovie 10 requires an Apple formatted external disc, MAC OS Extended (journaled) for the iMovie library to work correctly. exFAT is compatible with Mac and PC, but not sure if the iMovie library will be compatible with it. In any event, you should be able to use the Utilities app on your Mac to format the T5 SSD to MAC OS Extended (journaled) and that should make you good to go. I have not worked with a T% SSD myself, so can't speak from experience.
-- Rich