I fixed it by myself, the main issue is with the bones. All the Left side bones should be changed to the Right side bones. I needed to configure that by myself in Unity and it is working properly right now. Good model anyways!
thanks a lot, glad you got it working, thats exacly what it was. Ive uploaded a fixed version too, so anyone else wont have to set it up by hand. :)
Keep it up, man! Wish to see more PSX assets from you!