You can download ONLY one product at a time in EO Finder. Otherwise, you receive an error message "Max session number 1 exceeded".

When you try to download a second product from the Finder while downloading another one
If you cancel or terminate the download for some reason, you get a 60 seconds penalty, during this time an attempt to download another product displays information about the limit reached.

If you see this error message just wait one minute and run your query again.