All servers listed on Minecraft.Buzz require Minecraft Java Edition and are free-to-join. Minecraft can run on Windows, macOS, Linux, and can be downloaded here!
Find a server you like and copy it's IP address. Start Minecraft, click "Multiplayer", then "Add Server". Then, paste the server's address in the IP Address field. Click "Done" to confirm, you will then be taken back to the servers list. You can now click "Join Server" to play on it. If you're facing any issues connecting, here's some troubleshooting tips.