I've tried installing this several times, it doesn't create the .json file and even after creating it myself it still tells me unknown command when I try /Stackall

Check your oxide/logs for errors. This would imply the plugin is not loaded.

That means the file is unreadable and was modified in some way. This generally happens with tools such as FileZilla, where the encoding is changed while uploading. You can fix this by uploading in Binary mode instead.