I don't know current process, but I opened an account long ago when I needed API access for a client. Back then it asked for a site URL, which should be an established website, not coming soon etc. If I remember correctly, I think it asked for some banking information too, not sure. My account was closed after 180 days, no sales within 180 days, but then my account was a test account anyways...
Commission Junction is an Affiliate Marketplace, where business register their products. You apply directly to the merchants. Some of them have auto-rules for affiliate approval, for example they auto approve if they come from a certain country.