Using Raptor Liner on a primed tonneau cover?

I recently picked up a ready to paint Undercover SE bed cover for a steal. The cover is primed and ready for what I assume is to be painted a body matching color. I'd like to paint the bed cover in Raptor Liner.

My questions:

• Do I need to scuff up the bed cover or does the primer indicate it is ready to go?
• I've read a bit on some people using adhesion promoter, but I'm not sure that would be necessary on a primered surface?

For reference, I have this bed cover below:

• Cover