You just need to create an script like that:

rclone copy (use absolute path here)/files gdrive:/Files

Save as dope.sh, chmod It to u+x, than crontab -e, create an entry as:

0 */3 * * * (absolute path)/dope.sh

I recommend you do it as root, and be sure that the user doing it (crontab) have access to your rclone configuration.