Why did it do this and how do i fix it?

Please do not create new threads for the same issue.
If you have troubles following along provided instructions, either ask for elaboration on specific steps or pick a beginner-oriented task and tutorial to learn this information gradually, then return to this one.

For your beard to move and morph exactly like the facial area it covers, it must receive all data responsible for these processes from the facial area it covers.
This is accomplished by transferring data with Data transfer modifier. This is the only way, it cannot be simplified due to the high number of bones and morphs in this area.
I do not have your file in front of me to be certain about this, but it looks like your beard starts higher than any maxis ones, so you would not get accurate results by transferring this data from pre-existing facial hair. You can try to do this following the explanation below, if wont work, you will have to transfer weights and uv_1 from the head, as I explained previously.
- open s4s, click on CAS, in the search bar paste ymFacialHair_BeardMedium. Select any swatch, click Next, name it something, save. Export the blend file, open, rename s4studio_mesh_1 to Reference;
- import or append ( File - Append ) your sideburns to this blend file;
- select your facial hair, in Modifiers tab add Data transfer;
- choose Reference as Source object;
- enable Vertex data, expand it, enable Vertex groups;
- change Mapping to Nearest face interpolated;
- enable Face corner data, expand, choose Color. Holding Shift, enable UVs as well. In the drop-down below choose uv_1;
- change Mapping to Nearest face interpolated;
- click on Generate data layers and apply the modifier;