You do not need to be a rocket scientist to use this app.
rocket scientist
idiomOne qualified to handle or understand things which are very complex or confusing; a very intelligent person.
Origin
disputed originFrom rocket + scientist.
The instructions for the new coffee machine are confusing, but you do not have to be a rocket scientist to figure them out.
While the technical manual for the software is dense, one hardly needs to be a rocket scientist to grasp the fundamental principles of its operation.