Unless you're actively blocked from doing cron jobs (i.e., not on /etc/cron.allow or on /etc/cron.deny), then you should be able to run your own cron jobs.

Run crontab -e to open the cron job editor. If it's your first time you'll be asked to select a command line editor. You should probably choose nano unless you're familiar with one of the other choices.

Cron entries have the format

m h d mon wkday command

So putting in the entry

00 04 * * * bash script.sh

will execute your script at 4:00 am every day.

Save the file and cron will automatically implement it if there are not syntax errors.

See here for more information about cron.