Alright, so, if you export the EA beard that you cloned and look at it in Blender you'll see the whole thing is a mesh including the jaw and above the lip. Your beard isn't like that. It's got part of it on a mesh but parts are painted onto the skin. This is what's confusing the game.
Your beard will need to be made the way EA's beards are made. In Photoshop, open the base skin which you can download
here. Then open your diffuse as a PNG. A PNG will have a transparent background and this is what we want. Copy and paste your diffuse on top of the male skin, then merge down the layers and save the image as a PNG.
Note: my instructions are for Blender 2.78 but you can do the same in Blender 3.3. Open your mesh in Blender and in the outliner in the top left unfold the rig. Click the eye next to "head" so that the head is visible and click the little arrow so that the head can be edited. Select the head, and tab into edit mode. Press A so everything is selected, and in the UV editor, press A so that all the UV islands are selected. At the bottom of the UV editor go to image > open image and open the PNG you just made. Go into textured viewport shading. If you can't see the texture on the model press N to open the side panel, under shading choose multitexture. Ignore the right side of this screenshot. It's from a tutorial I made.
The head will appear green but that's because it's showing the vertex paint. You can delete the vertex paint if it bothers you but you'll need to add it back later as it's needed to work with the game's CAS sliders. (Your beard mesh isn't vertex painted at all so you will definitely need to fix this). In the tab with the upside-down triangle, where it says "vertex colors" just select the vertex paint and click the minus button to get rid of it.
If you're using Blender 3.3 the process is a bit different.
1. Select object and Tab into edit mode.
2. In the materials section, add a new material.
3. In the Surface menu click the little circle next to Base Color.
4. Select Image Texture.
5. Click Open and open the texture.
6. (may not be necessary) To see how the texture looks via the UV editor, open a texture the same way you would in Blender 2.78.
7. In the viewport shading area, the circle thing in the top right corner, click the downward pointing arrow.
8. Under Color, select Texture.
Now that you can see the texture on the sim's head you can select the faces where the texture exists then press P to separate them. In essence, you're separating the jaw and the area above the upper lip from the face--anywhere your texture is covering. You can use the knife tool (K) to cut new edges if you want and it helps to turn your tris to quads by using alt + j. Studio will triangulate the faces for you once you import your mesh. When those faces are separated go back to object mode and join them with your beard by shift-selecting both mesh and using ctrl + J. You can go ahead and delete the rig and all of the body parts so that only your new mesh is left.
Now, you can continue with the project. Your beard and the sim's jaw and upper lip are already weight painted but they'll need to be vertex painted. Hex #00FF00 is what you need, I believe. And given that the beard is made up of flat planes there's really no need for the polycount to be 11,880. Decimate will wreck your mesh so instead, press alt + J to turn your tris to quads then dissolve edges by holding alt to select entire edge loops or shift + alt to select multiple edge loops then X > dissolve edges.
Your beard needs a uv_1, as well. Without it, the CAS sliders won't work. If there isn't a uv_1 in the area with the upside-down triangle, under UV Maps, click the plus sign then rename UVMap to uv_1. You should have uv_0 listed first then uv_1 listed after. Then transfer the data from your reference mesh. Note: this screenshot doesn't explain this but under the apply button there's a box that you'll need to click and choose your reference mesh.
