>>327295149
I took a look at it myself, you should be able to just import the .fbx that comes in the download with Unity provided you go through the steps detailed in the comments.
The one big issue is that the animation obscures where the t-pose model would actually be. The right shows the model with the vrchat idle animation playing, which lets me eyeball where the viewball should be. From your posts where you took the model into VRC, it appeared your viewball was aligned with where the head was during the animation, and not where it would be standing upright.