Hi!
Thank you, I did not need the FTP information after all, I found the problem in the configuration.
On the Index Table options panel the “usp-” custom fields were not selected to be indexed, therefore the plugin was not able to search them. Once selected all the custom fields and generated the index table, I was able to search for the custom field information. You can check the configuration: http://i.imgur.com/ukUCrAh.png
I was testing on the duplicate search you have created. I’ve changed the keyword logic to “AND”, and it appears to be working correctly now. To test the configuration, I’ve picked a post and searched for “teems short 1362”. It gave me post “Faster” as result, as it is the only one having all 3 of the keywords all in separate custom fields – which is correct.
The data is stored correctly, it’s cleverly made on the front-end 🙂 I’ve also enabled the cron indexing option on the index table submenu, since adding a post from the front-end might not trigger automatic indexing. This will make sure to pick up new posts hourly even if the submission does not index them.