If you are trying to add the official libs then i suspect you tried to add the libs intended for version 5 (or nightly) to kicad 4.0.x
The new repos hold libs for kicad 5. They allow footprints with features not supported in v4. (This is explained on the download pages, in the readme file and in the repo description.)
Symbol libs also will not work as expected. At the least you will loose all documentation information if you open a v5 symbol lib with kicad 4.
At some later point there will be a backport of the libs but that will require writing a script to backport symbol libs. (We have one for footprint libs that just deletes footprints that are incompatible. -> results in a slightly smaller lib that is compatible with v4)
More details see: https://forum.kicad.info/t/how-can-i-install-a-specific-version-of-the-footprint-library/9269/2