Kate official repository is not on github but on KDE’s gitlab Utilities / Kate · GitLab as your sceenshot shows. Most KDE projects are on invent.kde.org , there can be mirrors though on github.
release are not build/distributed using release feature of github, and not yet through gitlab.
We had to do some migration of our building infrastructure (binary-factory.kde.org) and Windows and Mac OS build has not been reestablished yet, meaning we don’t provide windows and Mac OS binaries for Kate. We are working on reestablishing it, give it time.
The webpage needs to be updated in the meantime still.