Create Manual Subscription in Woocommerce with new order notificatin

I’m trying to create a manual subscription in Woocommerce but got some problems right now. Let me explain what i’m trying to do : We are an online personal trainers business. We are doing online programs and follow ups and we are selling subscriptions. So far, no problem.

Our customers are usually paying upfront for a 3 or 6 months packages with Paypal, and we have a Delivery Plugin which send a new order (0$) every month in our woocommerce dashboard. The way we are working with our trainers is that they are doing programs based on the orders in Woocommerce Dashboard, as when a renewal is appearing and a new order is up in the dashboard, they know that the customer is ready for his next month of plans. Sometimes, we got customers who wants to pay cash or by e-transfer. My goal is to create a subscription for those who are paying in cash/e-transfer with renewal orders, but where no payment would be taking (as they had already paying upfront for let’s say 3 months) –

So i would need a subscription creating a first order in woocommerce (no problem for that), but then another renewal order the next month, and same thing for the 3rd month – all while taking no money from the customer so I can’t link this subscription to Paypal. If i’m trying right now to use Manual Renewal in the payment method, no renewal is occurring after 30 days, nor 60 days.

Can someone help?
Thanks.