You need mods to get shared items working since the base game keeps everything separate between players. When extracting loot, each player's stuff counts for the team quota but stays in their own inventory, which means coordinating upgrades takes some planning. The big one to watch for is the shared upgrades mod that comes with repo enhanced - it syncs everyone's upgrades automatically so the whole team gets the benefits right when someone buys them.

Here's the technical bit: the host definitely needs the mod installed, and depending on which sharing features you want, other players might need it too especially for things like revival hp boosts and late-join inventory sync. Without mods you'll need to manually coordinate who gets what upgrades, so having a quick chat about equipment distribution before heading out is pretty crucial.

If you're running vanilla, just remember that communication is key since there's no automatic sharing system built in. The modded route basically streamlines everything, making upgrade management way more straightforward for the whole team.