I'm really confused why this is the case

So I am inputing a code that uses atom_style bio and it’s giving a message: ERROR: Unrecognized atom style ‘bio’ Can someone please tell me what I’m doing wrong?

There is no atom style “bio” in LAMMPS.

Where does it say that you need to use that?
Most likely you have an input written for a modified version of LAMMPS that is not maintained by the LAMMPS developers.

I apologize for the lack of information. I am trying to follow NUFEB for a sample simulation - they have. USER MANUAL.

This is not part of LAMMPS, so you are asking in the wrong forum. You need to discuss this with the NUFEB developers.