Thank you for your post. Maps purchased and downloaded with a Map Store account can be redownloaded on up to 5 devices by signing into your Map Store account. If you downloaded this map while not logged in, you will need to search for the map again on your other device in order to add it, as iTunes does not maintain a record of map titles purchased and/or downloaded.
If you did create an account and were signed in when you downloaded the map, to sign in, please open Avenza Maps and tap on Account (head/bust icon) where you can then log in to your account, select Download History and select the map linked to your account that you wish to download.
If you have any further questions or problems, please don’t hesitate to contact our Support Team directly through help.avenzamaps.com