It should exist on Google Play store and the page should show a link to that. Many won't just install APK, also people expect Android just install the updates.
Google Play store is not any guarantee or protection, and you can install BTCMap directly from github or by using Fdroid store that only contains open store apps.
You don't even have to install anything if you use web app from your browser and just bookmark page.
Another thing that I notice is that the map is loading very slow I think they need to improve and optimized the map to speed up the loading map process or I think if they can host it to a faster one like DigitalOcean or Google cloud it might improve the loading speed of the map.
This could be related with OpenSteetMap that is not going to be fast as Gmaps, but it would be counter productive to use Google clous when you are want to ditch google all together
A bit confused about the location submission. Does it mean users can only report a new store but will have to wait for the team to update the map? It sounds like that from the add location page. Would be awesome if it automatically shows up on the map and others can verify instead.
I didn't add any location yet so I don't know how everything works exactly.
If I understand correctly, some volunteer will check if application was correct and they will approve it or not.