In a game rip

From outer-wilds-unity-assets, put Assembly-CSharp, Dlls, Plugins, and Editor into Assets. Put Packages into ExportedProject.
Delete any of the existing folders while doing this. (If you have your own dlls in the Dlls folder, make sure to put those back. Same with any added packages in the package manager.)

In a project copied from outer-wilds-unity-assets

Same steps as the game rip, but additionally copy over extra folders in outer-wilds-unity-assets like Nomai Ruins.