On Mac OS 11.4
After you install the new Wappler 4 and you open a project that includes a docker setup Wappler will ask you if it should check the system setup.
If your answer with yes it will perform a check and identify the docker as not installed (but it is).
It will try to install and fail.
But if you just stop Wappler, start docker first, then start Wappler it will start with the message docker is correctly installed.
So I guess in the system check Wappler should try first to start the docker before installing it… actually no clue - just a logic guess 
Its only a small one but could cause problems for users that are not familiar with docker setups.
Otherwise an amazing product just got better - Wappler 4 - rocks!
Best