Character can't move when adding multi-parent constraint

I am following along with this tutorial

My end goal is to attach a gun to my characters hand and aim at the center of the screen with the gun. (A third person shooter). It seems like the best way to do this is with animation rigging. However whenever I add the multi parent constraint I end up getting an issue. It's a big one also, my character is not able to move. I am somewhat new to unity and this is my first forum post so if there's any information you need me to include just let me know, Thanks. View attachment 775171