Official comment

Only devices that are only available with more than 4 GB of RAM are able to download Map Pilot Pro from the Play Store. If your device is available in variants with less than 4 GB it is excluded from the supported device list. This is how Google handles device capability filters.
You can still install the app using the APK by following the instructions here:
https://support.dronesmadeeasy.com/hc/en-us/articles/8160429529876-Installation