How to register Subscriptions?

Problem/Motivation

On a clean Drupal 9 installation, I setup Stripe on test mode on a local site, configure public/secret keys and I add the webhook url on Stripe.
I select Webhooks for version 2017, I also tried 2022. And I select all events to be listened.
The Plan sync works well, I can see them appear under the plan list page, but subscriptions are never created after a user signs up for a subscription. I wonder why is this not populating?

Under the documentation of the module it reads
The 3.x version of this module requires the Stripe customer portal, which allows users to change plans and credit card information more easily. Is this documented in more detail somewhere?

Steps to reproduce

• Navigate to: stripe_registration/subscribe
• Click on one of the stripe products synched from my Stripe account.
• I am redirected to Stripe to finalise the payment (I enter test card details) and check that the payment was successful
• I am redirected back to my local site.

When looking at the subscription list, it appears empty.

I am not seeing any errors in the log, all I see is that the redirect to my local homepage has the`?checkout=success` appended at the end.

I am not sure if this problem might be Drupal related, or maybe I am missing some configuration in Stripe.