Missing Textures In 3D Create A Sim Background Override

So I downloaded this Rupaul's Drag Race runway create a sim background override from gramsims. It's super cute and 3D, which I love, plus you don't see many 3d create a sim background overrides, so I ran to download it. All was well until i actually loaded up CAS and noticed that the background looked nothing like the preview pictures, or even how it looked in sims4studio. It had missing textures. I've tried deleting uv_1 in blender which was a common fix for this problem when i googled it, didn't work. I tried playing around with the shadow lod, didn't work. I'm desperate atp because I really want to have this in my game and have it look exactly how it looked in gramsims's preview and how it looks in sims4studio. Below is pictures of it in sims4studio and gramsims's preview and the very last picture of it is in game. I'll also provide the package files so you all can inspect it, because i'm stuck.
gramsims's original version UNTOUCHED: mega.nz/file/pd1ATQ4A#HWD6tOr2uWDdq7dkYJBaeRluVMR91O95rpXe8qlMDhU
the version i tried tweaking with in an attempt to fix the problem but it didn't work: mega.nz/file/kctQDKoS#vGvtaK2kD_ddrcSkygSgM2vBGNEw5iNp1Y7dyrhYPOk

how it looks in sims4studio:



how it looks in gramsims's preview: 



how it looks in game: