Cannot upload video files

I’ve been building the LMS site with the Tutor LMS and would like to integrate the VideoPress as the video hosting, but the VideoPress menu doesn’t show up when all the users, including the admin, click the Add Media button in the classic editor of the WP, and all the users cannot upload any video files with the classic editor on the frontend unlike the following instruction describes; https://jetpack.com/support/jetpack-videopress/video-hosting-classic-editor/ and https://jetpack.com/ja/support/videopress/#jetpack-%C3%A3%C2%81%C2%A8-videopress-%C3%A3%C2%82%C2%92%C3%A9%C2%96%C2%A2%C3%A9%C2%80%C2%A3%C3%A4%C2%BB%C2%98%C3%A3%C2%81%C2%91%C3%A3%C2%82%C2%8B.

Only thing I can do now is that I (admin) can upload the video files from VideoPress under Jetpack menu in WordPress (backend), but the other features don’t allow me to operate; for instance, when I try to upload the video files via WordPress.com (/media/domain name/), the error message “1 files could not be uploaded because an error occurred during the upload.” has shown up (please see the following image for reference.)

https://snipboard.io/7Yx6KN.jpg

How should I fix this issue? I’ve deactivated/deleted/re-installed/activated many many times, but the issue has not been fixed. Also, many errors have occurred and I’m so frustrated. Ideally, I’d like to allow all the instructors who provide video contents to upload them and get their video links by themselves. Pease let me know the solution for that.

Thanks,
Atsushi