Game crashes upon start.

Okay, so I've been trying to play Valhelsia 3 the past 3 days.. with no luck, no solution in sight.
I keep getting error code 255.
Keep in mind I'm using a Mac OSX Latest version. And latest Hardware.
The Admin of Valhelsia seems to think it's Minecraft at fault

I have another person with exact same OS as I have and it works for him.
Got Java & Forge installed. as I should have.
What might cause this?
Here is the crash log.. keep in mind it's really long.

https://paste.ee/p/6YkbD#