Team Numbers ..?!?!?!

I am making a college team and the numbers dont match up with the E.F. Offical Rules saying " Numbering System 10-19 quarterbacks, 20-49 running backs, 50-59 centers, 60-69 guards, 70-79 tackles, and 80-89 tight ends and receivers"
I looked online at my schools roster and some of my players have numbers that do not fall in their or this numbering system.
DO WE HAVE TO FOLLOW THIS..?
Lil b