The plugin gives you also the possibility to create subscriptions from the backend. Go to WooCommerce > Orders > New order. Select the customer from the related field, then the subscription-based product(s).
Click on Add to add the subscription(s) to the order then click on Create to create the order. Now go to Order actions and select the subscription from the dropdown then click on Update.
Please note: if you are creating an order with 2 or more subscriptions, you must select them one by one (click on Update after each selection) in the Order actions. In this way, all the subscriptions added will be activated.
After creating the order with subscriptions, users can make the payment directly from their My account page or through the link sent with the email. The payment method selected for the payment will be used to pay the next renewals. To correctly register the gateway for recurring payments, it is essential that users pay also for those orders with €0 as the total amount.