If your only application of butyl tape will be this fan, Amazon sells an "install kit for 4.49. Should be enough butyl for two wraps around the vent hole.
https://www.amazon.com/dp/B000EDQQBU..._VzbJDbBZ31DDQ
The Dicor sealant you'll need comes in a few color. Pick the one that matches your existing roof color. Make sure it's the self-leveling lap sealant, not the "non-sag" variant for vertical surfaces. Easy to buy the wrong one.
Here's a tube of it in white:
https://www.amazon.com/Dicor-551LSW1...dp/B003YJLIW8/
Preparing the vent hole for the new fan, make sure the existing butyl and sealant is removed as much as possible. That was the longest and most labor intensive part of my MaxxAir installation. It was helpful to have some plastic putty knives and plastic automotive trim removal tools on hand to aid in the process. A little mineral spirits (applied to a rag) to clean the membrane prior to laying down the buytl was also helpful. Dont use too much though.
Good luck.