I've created a package inside Unity called Wave Survival Multiplayer. Inside this package are many features including: Multiplayer, Zombie A.I, Barricade System, Wave Spawning System, Basic Inventory, Currency System, Multiplayer Lobby, Player Tags, Multiplayer Scoreboard and much much more.
Price for the package: only $5.99
Feel like taking a better look at it? Check it out at Sellfy: https://sellfy.com/p/F2VH/