Modules should click together. I printed on my Bambu Labs P1S and adjusted the tolerance so they click together well, but your printer might have slightly different tolerances, so beware.
Takes a little massaging for all tabs to click in. You can usually look at the slot/tab interaction to see if all tabs are locked in.
Future
There are a few changes/modifications I want to make in the future
Slightly larger lip (my son has his on carpet and sometime cars can still roll out)
Add versions of models with different tolerances on clicking components. Maybe a test piece that people can use to test which fitment they need.
Add a car ramp that lets the cars drive out of the garage