Re-rigging SFM model to playermodel/npc rig

Hi, I was wondering if anyone could help me with rigging a model from SFM so it could be used as a playermodel, the problem is, I don’t know where to begin. is the model in mind.
The model already seems to have the same bone names as the rig needed but when I tried adding the player animations it created an eldritch abomination instead.
If anyone could point me in the right direction I’d really appreciate it. I’m using Blender for this.