Here's the main updated setup video for 4.0. Definitely back your project up before upgrading. 4.0 has several renamed and upgraded resources so you'll see some empty properties in the node inspectors (BuildingState instead of BuildingSignalBus for instance). Placeables themselves are mostly the same. There is also an updated setup guide in the README.md let me know if you have any issues (Discord invite link also in the README)