2019 client and newer using http for guild emblems, hotkeys and some other.
and this api server add support for most of http things what need for client.
need configure url in external settings file to point to api server.
I assume rathena already has these quests set up. You could in theory add them to hercules and debug, but those jobs are not supported yet, so the scripts will not work until the 4th job EAJs are added.