For all of the "approved" mods, you can download them directly in-game with the click of a button!
For unapproved mods, you'll need to install them yourself manually.
Whilst approved mods have been tested and are safe (outside of a few bugs), please be careful when downloading unapproved mods from unknown sources!!
If you're playing on Windows or MacOS you can use the official "Sideloader", which will automatically read the mods you have downloaded, let you add a mod's zip folder (from Mod List), and manage your activate mods - all in one place!
If you're launching the Sideloader on MacOS, you might end up getting the following error: "APICO Sideloader" is damaged and can't be opened. You should move it to the Bin. This is expected, and is a general macOS feature protecting you from opening unknown apps downloaded from the internet. You can fix this by following the instructions on the GameMaker website.
If you're playing on Linux or do not want to bother using the sideloader then you'll need to manually install the mod yourself.
First off download the mod's zip folder from Mod List!
You will then need to find your mods folder, in Windows this will be in "%localappdata%", in the APICO folder (not your installation directory):
Unzip the contents of the zip file to the /mods/ folder, and re-name the folder to match the MOD ID listed in the Mod List if it's not already:
Finally go into your "settings.json" file in the /saves/ folder, and edit the "downloaded_mods" list to include the mod you just downloaded:
With that all done, you'll see the mod listed in the Mods menu, albeit marked as unapproved!
You can then activate the mod and load your file as normal.