DISCLAIMER

Install a version of Unity 2019.4.x, to do this, download Unity Hub, and install a version through the client, the latest the better. Install with Mac & Linux support, without this support, Mac and Linux players wouldn't be able to play on your map without issues.

If you have any mods/assets that need updating your gonna have to bundle on this version. If you're on a Curated project, get all the assets into one Unity Project and bundle from there.
Make sure to import the "Project" and "Standard Assets" unity packages into your project. (Unturned>Extras>Sources>).

Awhile back a friend in a server I'm in was having issues with bundling, so I made a video guide for him. It's not the greatest production wise and I'd like to replace it with something smoother, but for now here's a rough video guide. Due to explaining Unity as a whole, if you are already familiar with the engine you can safely skip towards the start of the setup, there's a timestamp in the description for that.

This part ain't hard, just takes a lot of time, here's what you do.

For simplicity's sake, we'll pretend we're making a Texas map. You can name your root directory in Unity whatever you want, but we'll be going with "TexasMasterBundle". Assuming you already have some assets made, you'll want to organise them into a hierarchy that matches the .dat structure in your mod's bundles directory. The structure has to be exact, otherwise the game can't link your assets to the .dats you've made for them. For example, if a tank top in the Map's files is located at Texas>Bundles>Items>Clothing>Shirt>Tank_Top then in unity it would be located in Assets>TexasMasterBundle>Items>Clothing>Shirt>Tank_Top. The Tank Top's folder should look something like this:
In Unity, you're going to need to make an "Asset Bundle" (You can do this by selecting any .prefab in Unity and going to the Inspector tab, at the Bottom right you should see a tab that reads "AssetBundle None" click on it, and click new in the popup, type in the name of the Master Bundle, something like Texas.masterbundle (you must add the .masterbundle suffix for it to work). Give your root folder (TexasMasterBundle) the AssetBundle tag. Now you're finally ready to export. Open up the MasterBundle tool and select the bundle you want to export(Located at Windows, Unturned, MasterBundle Tool). If you're just testing your mod, there's no need to select "Multi-Platform". You also need to have installed Mac & Linux support when installing the Unity editor for it to work.

Now, for the final and easiest part, you need to make a .dat file and put it into your Bundles folder. It needs to be called "MasterBundle.dat" the contents of the .dat should be as follows
(The texas.masterbundle has to be lowercase)
Of course, replace the Texas part with your maps name/codename (peaks, cliffs, etc)
Your Bundles folder should look like this (of course there would prop be more folders)

In case you applied the Masterbundle Tag to all of you assets, a handy thing you can do is to go to the inspector tab and click "Filter Selected Name" this will show you all the assets with this tag.


If any part of this guide didn't make sense to you let me know and I will try to make it more clear.
Thanks for reading, and happy modding!