The files need to be gzipped. Use one of the many released gzipper to convert your .dat to .gz
or simply
You can place .dat files into your raw folder in cache → data → raw
https://www.rune-server.ee/runescape...e-gzipper.html
https://www.rune-server.ee/runescape...zip-unzip.html
https://www.rune-server.ee/runescape...p-utility.html