Gmod crash when join a Zombie Survival Server (Mac)

When the loading screen reach “Sending Client Info”,the game crash.
Any help?

Mac Specifications:

Processor : 2,5 GHz Intel Core i7
RAM : 16 GB 1600 MHz DDR3
Graphics : Intel Iris Pro 1536 MB
Video Card : NVIDIA GeForce GT 750M with 2GB of memory GDDR5