Just installed this and while testing, I received a similar error.
After that when I click on my download menu, the component works fine. Then when I click on a category that has 0 files that shows properly but when I click on the category that has 1 file, that is when I receive the above error message.
mysql Σφάλμα [1064] : EXECUTEURI: index.php?option=com_downloads&task=category&cid=1&Itemid=138Message: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 0,1' at line 1LIMIT 0,1