unity (free) to steam...

I’ve made a game and was looking to release it on Steam. I only have the free version of unity and can not afford the 1,500 pro version. Is there any add-on that I can buy to get my game on steam to start marketing.

Steam requires the use of plugins, which makes it impossible to use without Pro. (Note that Steam requires high quality and some luck to get accepted; it’s not like iOS/Android where you can pretty much put up whatever you want.)