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, Samsung Galaxy S6...