It cannot be downloaded with Adobe Creative Cloud Express.

Hi @みずき98A2 

Okay, please scratch my earlier reply. Yes, you can export videos directly to your local computer as well as share the videos. I was able to successfully create and download a test video as an .mp4 file. I used Brave browser with Windows 10. I don't see any issues. Please check that your browser or antivirus software is not blocking anything. Try logging out and back in with your Adobe ID. Switch to another browser as a test.

Go back to the home screen to see if your video is there. Click on the ... menu and duplicate the video. Then, go back and remove some frames to see if you can successfully export again. It may be that one slide is hanging everything up.

See instructions here: https://helpx.adobe.com/express/using/create-video.html