It seems like the public repository on GitHub for the Magic Leap SDK is no longer maintained, since the latest version available via GitHub is 2.3.0 (GitHub - magicleap/MagicLeapUnitySDK: Magic Leap Unity Developer SDK). Developers have to manually download the latest SDK via Magic Leap HUB and link it locally to the Unity PackageManager.
This may work, if you develop and deploy apps on one single machine, but if you want to share a repository on multiple machines or use a building agent, this means that all the packages need to be placed inside the repository and pushed to it, causing a big overhead. This could be much simpler, if the public repository for the SDK would be kept up-to-date, like it had been until v2.3.0