Partner's PC freezes when opening level

When I open up one of the levels in my game (it’s a big level with a lot of megascans assets) it loads fin. but when my partner tries opening it up on his computer, everything freezes. We both have 16 gigs of RAM and he has an I7 and I have a Ryzen 5. We have tried everything but nothing is working. Any help is appreciated.

Thank you.

If it’s not a packaged game then your partner has to also compile all the shaders etc. Have they done that?..