Seeing as I've gotten it to work perfectly on FM20 and have helped others to do the same I thought I'd post instructions on how to do it here.
The issue on older versions of FM is that you cannot import the "is newgen" filter provided and the tool only works on 10-digit UIDs so there cannot be any real players in the .rtf file you save, so you have to make it yourself which requires the in-game editor so you can filter for hidden variables. Follow the instructions provided, but on step 13 instead of importing the filter you go into "Edit Search", click the arrow next to "Add Condition" -> "Hidden" -> "Is newgen". Then you set the condition to "Is Not" and leave the field blank. That filters the search to only newgens (this is exactly what the imported filter does). Make sure this is the only active condition, so you don't filter away any newgens (and that you don't exclude your own players, the provided instructions tell you how to do this). Then you continue to follow the steps in the provided instructions as written. I got this to work on FM20 but it should work the same on older versions of FM as long as the newgens have 10-digit UIDs and you can import the "SCRIPT FACES player search" view so the correct variables are included in the .rtf file.