In order for you to play MXGP3 - The Official Motocross Videogame on macOS with minimal graphics settings, your computer must meet the following requirements
Operating System:
Mac OS 10.13 (High Sierra) or later
Processor (CPU):
Intel Core i5 or better
Memory (RAM):
8 GB RAM
Graphics Card:
Metal 2 compatible with 4GB VRAM
Storage:
13 GB available space