You can have a look at a tutorial video

Follow the steps here[theindiestone.com]

The text "AutoLoot ON" (or OFF) on your inventory panel is always displayed when the mod is active.

Ensure the mod is Enabled for default configuration BEFORE you start a new game.
From Main Menu select MODS and ensure the mod is Enabled.

You may not know there is a mod selection by default and a mod selection for each game save.
Ensure the mod is Enabled for the specific save of that game.
From Main Menu select LOAD > your own save game > MORE... > Choose Mods... and
ensure the mod is Enabled.

You are right, it should open the Configuration Menu.
Some mods are (and will) break vanilla items internal lists.
Necroforge is the most used among them.
You need to deactivate the problematic mod and then you will be able to set your configuration.
Note that you can reactivate the problematic mod once the configuration is saved.

On you own Inventory Panel, there is a button AutoLoot ON.
Click on AutoLoot ON to turn it OFF.
If the button is not visible, increase the width of the inventory Panel UI.
Alternatively, you can inhibit furnitures and vehicles from world context menu.

You can activate/inhibiting a worn bag via context menu.
You can restrict the category of items accepted by a bag through a contextual "Filter" menu.
You can give a priority through context menu to each bag and main inventory (but not the KeyRing).
If two bags are active with the same priority, the best reduction ratio will be used first.

Ensure you've set AutoLoot ON from your inventory panel.
Check that the item you expect to loot is active in your current configuration.
Check with modoptions that the corresponding container source is active: dead corpses, ground, bags, furniture, vehicles.
Check that you have enough remaining space to autoloot.
You should not do it but you can also, from mod options, allow unlimited overweight.
Ensure the source container is not inhibited (right click)

Ensure you've set AutoLoot ON from your inventory panel.
Check that the item you expect to loot is active in your current configuration.
Check that you have enough remaining space to autoloot.
Ensure the source container is not inhibited (right click)
Ask your server team what the sandbox options are for AutoLoot mode.