Zwift requires a GPU that supports the Metal API. It looks like that starts with the 2012 model.
NVIDIA GeForce 9400M is too old???
It is an onboard GPU, no dedicated memory. Started 2008.
I can’t imagine it has the power for Zwift.
If it supports Apple’s Metal API, and your operating system is 10.14.4 or newer, then it might sort of work (ie, the game may load at all). Probably worse than running on a phone.
Hold down the option key and go to the 
menu, choose System Information, click on Graphics/Displays, and look for Metal Support or Metal Family. Do you see anything there?