Build ATAK from source with one command.
See talentedbrute/buildTAK for a similar build script that does not use Docker.
Because there are several large file downloads and compilation takes a while, we recommend running this in a screen session on a cloud machine.
Make sure Docker is installed (see https://docs.docker.com/get-docker/).
Run:
docker build --progress=plain -t atak-build . 2>&1 | tee -a out.log
Copy the APK out of built image:
docker cp `docker create atak-build`:/AndroidTacticalAssaultKit-CIV/atak/ATAK/app/build/outputs/apk/civ/debug .
The APK will be in debug.