This means that there is a version of ES running on the machine, and it's an old version that you should not use right now for something new. It might be part of another piece of software that depends on ES or something like that. You could try
curl -XGET <host>:<port>/_cat/indices
...to see what is actually in there.
You might want to install ES 2.4.x from our website and have it run on another port then 9200 if you're not sure about where this ES came from.