Download this repository
Open the downloaded ZIP file
Drag and drop the script(s) you want in the folder they need to be placed in.
If no instructions are provided for the script you want then simply follow the instructions given in How do I use a compiled script?

Just keep in mind that this downloads a copy of this repository at the moment you download it.
If a script is updated after you downloaded this repository and you want the new version then you will need to download this repository again.

How do I use a compiled script?

Follow the instructions in the documentation

Open the start menu and go to %localappdata%\Plutonium\storage\t6.
If the script should be loaded for both the multiplayer and the zombies mode then drop the file in the scripts folder.
If the script should only be loaded for the multiplayer mode then put it in scripts\mp.
If the script should only be loaded for the zombies mode then put it in scripts\zm.

Note that you can use map_restart in the console to quickly restart your current game and reload scripts.

How do I compile a script?

Download GSC Tool
Read the instructions to compile a file

It should look similar to this
gsc-tool.exe comp t6 "C:\Users\Resxt\AppData\Local\Plutonium\storage\t6\scripts\mapvote.gsc"

If after opening the file you see that it has a lot of non readable characters this means that it was successfully compiled.

What are compiled and source scripts?

Before downloading a script it's important to understand what compiled and source scripts mean.
A source script is the script in a human readable form (a text file), this is how the script is written.
A compiled script is simply a source script that has been compiled by a compiler to make it readable by the game.
At the time of writing, T6 cannot read source scripts so you have to compile them to allow the game to read them.

So if you only want to use a script and you don't want to edit it or review its code then
you can simply read How do I use a compiled script?.

All of my scripts always come as two files:

script.gsc (compiled script, ready to be used)
script-source.gsc (source script, made to read the code and eventually edit it, cannot be read by the game, needs to be compiled)