to run a script as system user, i have used psexec but i use task scheduler.
i mount to a folder, not to a drive letter
rclone mount media: b:\mount\rclone\media --vfs-cache-mode=full --rc --read-only --attr-timeout=1000h --dir-cache-time=1000h --poll-interval=0 --log-file=log.mount.media.txt --log-level=DEBUG
when i need jellyfin to scan my media, i prime the mount first, as per @VBB
Google Drive, Plex, Windows 10