Garry's Mode wont load on steam. PLEASE HELP

SO I recently purchased Garry’s mod through Steam. Upon opening it up It just becomes stuck on a blue loading screen. It never ends.

Im on a Mac, please halp me. Steam has shitty support. Im starting to become hopeless.

Thank you <3

Have you tried reinstalling the game?
Have you tried restarting your computer after fresh install?
Have you deleted client registry.blob?
Have you defragged?
Have you validated?

If you do all of these, I promise it will fix it.