There is a folder *additional* on your ftp account.
You should first upload jpg-s and then check their image ID-s here: https://www.dreamstime.com/uploadhistory.php
And then rename your eps files with corresponding numbers and upload them to the ftp account's *additional* folder.
Here you can find the description: https://www.dreamstime.com/ftpupload.php
A little bit complicated. I prefer to submit jpg and then upload an additional format on the image submission page. Then you don't have to rename your eps files.
Hope it helps.
M, Adobe CS6...