Dye1222 If you still need help, please let me know whether you're willing to use mods, at least while troubleshooting. I'm not sure they're necessary, but they could at least make the process easier.
And who is letting your sim into the house, and is the other sim home? I believe the place is owned by a couple, with no other residents.
I played through this adventure chain a few days ago myself, so I know it works in general... with mods in place, and in Windows. But it's very possible something is broken in your instance of Egypt. So let me know whether it would be a burden to revert to before your sims arrived there, or to send them home and go back again in a sim-day or two. Please also let me know whether your computer runs Windows or macOS.