Thank you for your post.
What I suspect has happened is that you purchased the map without being signed into an account. This is a common issue with iOS devices since Apple does not force users to create/sign-in to an account prior to purchasing maps. This causes purchases to be unassociated with an account and when the user changes/upgrades to another device the purchase does not appear in the Purchase History or there was a communication error when you were purchasing the map. There is an easy fix for this.
I just need a copy of your Local Purchase History, this will show me your purchases and then I can find them in our system and properly associate them with your account.
To send the Local Purchase History, please open the app and go to Settings > General > Debug Settings > Avenza Map Store Settings > Local Purchase History and email this information to firstname.lastname@example.org. Once I receive this and verify the purchases in our system, I will add them to your account for you to access on up to 5 devices by logging into your account (head/bust icon).