You should be able to see your subscription for the publication here. If you do you will be able to restore it in-app. If you don't, then you don't have an active subscriptions associated with the Apple ID for the device you're on.
How do I restore my subscription to the app?
Open the app and go to Settings
Click 'Restore' in the Account section
If your subscription has been found then you will be able to access the editions from the storefront.
What do I do if that still doesn't work?
Send logs by following this guide - https://pugpig.zendesk.com/hc/en-us/articles/4407428595089