Creating a subscription in Google Play

[TheRL]

Hi there
I’m trying to set up a monthly subscription in Google play for my app.
I cannot find any documentation on this.

When I go to subscription in Google play, it asks me to upload a APK file but all I have gotten from the build is a aab file.

I would appreciate any direction with this.
Thanks

[TheRL]

I have read the documentation and it says just to click “create” to start creating my subscription.
I don’t see a create button.

My app is in open testing.