Can I give a user a trial on a subscription plan for registering with an affiliate and making a deposit with them?

Here's an idea to make it easier for users to get activated in the app. We can't give free access by default, because we incur costs for each activated user in the app. Can I give in-app access for registering with a partner and making a deposit with them, and then give the user a subscription plan for free for 30 days, without IAP and auto-renewal? The rules say you can't use third party payment methods, but it's part of the app that the user has to register with a partner, just for making a deposit to the partner, we give a trial gift.