The last environment variable override you have there is the closest… the following did the trick for me, just keep in mind the admin user is created shortly after initializing the database on the first run. So you’d have to remove the running container and try again if you don’t get right the first time.
docker run -d --name camunda-run -p 8080:8080 -e CAMUNDA_BPM_ADMIN-USER_PASSWORD=boop camunda/camunda-bpm-platform:run-latest