Humanoid animations to Sketchfab

This is my first time using Unity and I followed this tutorial, so I'm a bit lost and intimidated by the software.
I've finished the tutorial and I'd like to upload what I did to Sketchfab but the Sketchfab add-on isn't compatible with humanoid rigs. I thought using an fbx exporter would help but the animation in the outputted fbx is broken. I looked into a tutorial that converts Humanoid to Legacy or Generic and wasn't able to figure it out, I think I need to do something to the animation first.

Anyone know what I can do to achieve this?
Links to tutorials appreciated.