How To Install a Mod From Github - KSP-RO/RP-1 GitHub Wiki
Don't know how to install a mod from Github? Have no clue what folder belongs where? Never fear, here's a guide.
There are two main ways to install a KSP mod off Github. We'll go over both of them: 1) downloading a branch and extracting the /GameData contents and 2) installing from a packaged release.
Grabbing a branch (the common way to install)
1. Choose the branch you want (you will generally want master).
2. Press the green "Clone or Download" button and choose the the zip option.
3. In the downloaded zip, navigate to the GameData folder.
4. Copy the contents into your KSP GameData folder.
If you are updating or replacing a mod, you will likely need to delete the preexisting folder(s) of the same name before you copy it over.
Note: this isn't always the case, occasionally mods will just need to update a single file in an existing folder (ROTanks does this to /GameData/RealFuels/Plugins/RealFuels.dll), and thus will only contain that file in the packaged folder. In this case, removing the existing folder will break your install. Best practice is to always check that the contents of both folders looks reasonably similar before replacing the old one.
Downloading a release (the less-common way to install)
1. On the release page (looks like this) there will be one or more zipped folders. Click it to download.
Note: for future reference, to navigate to the releases page from the main github repository page, click the releases button.
KRASH is the example because I can't be bothered to replace the image, but there is no longer any reason to install KRASH. KCT simulations (built into RP-1) are less buggy and more convenient.
2. Extract it into GameData.
The contents of the .zip will vary, but generally there will be a /GameData subfolder you will copy over into your KSP GameData like the normal method.
Note: as for all things github, when in doubt, consult the mod wiki or repository readme (hopefully the mod author wrote one!) To find the readme, it will be in the downloaded branch/release folder as /README.md or displayed on in pretty markup on the main repository page when you scroll down.
Congrats, that's it!