The batch file -- which is named "download.bat" doesn't do well if it is saved somewhere with spaces in the folder name. For instance, D:\your folder name\jav-it.  You can do two things here

move the jav-it folder somewhere where it's not in a folder which has spaces in the name, not even nested as in D\:folder one\folder\jav-it

Edit the batch file -- if you know how to do that, you're already advanced so i'll keep that short. change the %CD% (current directory parsers) to "%CD%". The thing basically errors because CMD expects something like "D:\your folder name\" instead of D:\your folder name. 

Easy to follow? Errrrrr no it's not, the guide goes straight to using download.bat and catalog.bat without even telling you how your supposed to put those 2 files inside the same folder as javit.exe

What I need is for it to catalog my 3000 ish titles and then download them all to an external HDD as the primary backup before R18 closes.

So no what I am seeing is not easy to follow, I can't even change my file location on the command prompt to where the folder is...