There are a few issues:
1. It seems like you are working in a different version of blender than what is linked in s4s settings;
2. If you were to open thesimsobject.blend, you'd see three meshgroups: the table and two type of shadows under it. To replace all of these files, your blend needs to be structured the same way and have corresponding cuts ( so to replace the original table, yours needs to have cut 2 ). Instead, currently, the package has two tables and one old shadow.
3. Some parts of the mesh are facing the wrong side, which is why they look like they are missing in s4s.
4. The item's polycount is 4 times higher than maxis most complex meshes. If you plan on sharing your content with others, you must be conscious of it;
5. To bake textures right, uvs must not overlap.
6. A table should have uv_1 that matches uv_0
Do the following:
- in s4s settings change the blender path to blender.exe in the installation folder of the version of blender you prefer to work in;
- in s4s main menu choose Create 3d mesh and click on Object, filter the catalog by surfaces and two meshgroup, choose the right table, Next, name it something, save in Mods folder;
- export lod 0, open;
- select the table, check the cut number and delete this meshgroup. File - Append - goldok.blend - torus, Append;
- select the table, give it the same cut and switch to edit mode. Enable Face orientation. You will see red faces. Select the big one and press G Z, lower it to stop from intersecting with the rest.
- see the red row of faces on the rim of the table? they intersect, make it harder to select edge loops and increase the polycount dramatically. Enable X ray, click and drag to select them from the side view, Delete - Vertices. Then Alt-click on border edges and Edge - Bridge edge loops;
- somewhat select toruses, press Clrl L to select them fully, Edge - Un-subdivide;
- in uv editor, with uvs of toruses still selected, press S Y and shrink them vertically until they are thinner;
- the rest of the table needs to be unwrapped properly. Alt-click on these edge loops to select them, then UV - Mark seam. Press Ctrl L and UV - unwrap. You'll see that one uv island is curved, you can straighten it. Zoom onto the middle of it where uvs are the straightest, enable Snapping to Vertex, select one vertex, press G Y and align it with the perpendicular one, do the same with the other one. Align the other two with G Y until you have a perfectly straight rectangular. Select that face, Ctrl L, UV - Unwrap - Follow Active squad;
- select all uvs with A, Uv - Pack islands, change Margin to 0.02;
- rename a uv map to uv_0. Duplicate it and name uv_1;
- click on +, double-click to rename to transformBone, in 3d view select everything with A, hit aAssign;
- select everything, Face - Shade smooth;
- add Edge split modifier and apply;
- adjust the shadow plane underneath, save, import in s4s;
- now you can bake textures.