Adobe Express Videos on Chromebooks

Has anyone else experienced trouble creating a video on a Chromebook? I have tried from both a teacher and a student account and each time I attempt to add a video file to a video creation project, I get an error message telling me that it is an unsupported file type. I get the same message if I try to use the Adobe video converter that is linked.  This is true whether the original video was recorded using the native Chrome OS video recorder or a Chrome extension such as Screencastify.  This has prevented us from being able to use the Adobe Express video creation tool, as it is nearly impossible to import a video the students have recorded themselves.