What crankset and components for BB30?

I purchased a cheap CAADX frame, so I can build it from scratch reusing components I have at home while learning how a bike works.

It comes out that the bike has the BB30, and I am unsure what I actually need. I understand I need a compatible crankset but… a part of that, what do I need between the bearings (see picture) and the crankset? I have checked online and I am still a bit clueless.

Thanks