No, you don't need a real estate license to be a co-host.
The best way to be paid, in my opinion, is a percentage management fee. Agree upon a percentage with the host, and then you'd earn that percentage of the monthly earnings.
Ideally you are adding a level of service for the host through handling all check in, check outs, guest communication, cleaning, repairs, etc. This should allow for more 5 star reviews and Superhost status. Allowing you in the end to raise the nightly rate, which in turn would raise what you earn.
Sierra Kluson
Keller Williams Realty St Pete