It works now

common/users/cameron/default.nix

@@ -5,7 +5,7 @@ with lib; let
 in {
   options.user.cameron = {
     enable = mkEnableOption "user cameron";
-  }
+  };
 
   config = mkIf cfg.enable {
     users = {
@@ -17,7 +17,8 @@ in {
 
         uid = 1000;
         group = "cameron";
-        extraGroups = [ "networkmanager" "wheel" ];
+        extraGroups = [ "wheel" ] ++
+          (lib.optionals config.networking.networkmanager.enable [ "networkmanager" ]);
 
         home = "/home/cameron-nix";
         createHome = true;

flake.nix

@@ -1,5 +1,4 @@
 {
-
   description = "My nixos config as a flake";
 
 
@@ -18,11 +17,10 @@
         system = "x86_64-linux";
         specialArgs = inputs;
         modules = [
-          ./configuration.nix
+          ./hosts/nixos/configuration.nix
         ];
       };
 
     };
   };
-
 }