Installation (for users)
It is normally not required for users to install Cardinal Components API, as mods should bundle it with their own releases. If a built jar is still needed, either because a mod did not bundle it or because a newer version than bundled is required (eg. critical bugfix), there are 2 main ways of obtaining it.
Built jars can be found for every version in the Releases tab on GitHub. Just find the version you need, then click on the Cardinal-Components-API-<VERSION> link in the assets drop-down.
Cardinal Components is also available on Curseforge. If you are a mod developer, you may want to link to that page by declaring Cardinal Components as an embedded library of your mod.