VP of Marketing.
Whatever you do, at $4m in ARR, don’t hire mid or low-level marketers yourself. It’s way, way too late. There’s too much to do. You need the head of marketing in place — now.
Hire a true VP of Marketing and give her (x) a revenue commit and (y) a budget to hit it.
She’ll figure out which hires to make to hit the plan out of that budget. It may be 4 hires. It may be 0 hires, and she prefers to spend that money on outside resources or programs. You shouldn’t be figuring that out. You are too big and far along.