Any Soco creator can apply to the program, with no invitation needed and nothing to email. Your affiliate account and your payouts are run by WinWinKit, Soco's affiliate partner, so withdrawing your earnings happens in WinWinKit, not inside Soco.
How to apply
Update Soco to the latest version on the App Store first, so the Soco Affiliate Center is there:
Open the Soco app and tap the account icon in the top right of the Home screen.
On the Account screen, tap Soco Affiliate center.
Tap Join and fill in the application form.
Once you're in, the Soco Affiliate Center shows your affiliate link and your code.
How a referral counts
For a referral to be linked to you, the creator you refer enters your code in the Soco app, on the "Have a referral code?" screen they see after they sign in. Without your code, it isn't.
Your code is worth entering for them too: the creator you refer gets $5 off their first month and a 7-day free trial when Apple offers them one.
Withdraw your earnings
To cash out, open the Soco Affiliate Center and tap Withdraw. WinWinKit opens, and you withdraw your money there once you get an email.
Next steps
More on working with Soco: