Unfortunately, that company's products seem to be for high voltage and/or large transformers. The transformer I have is a tiny 1.5-2 ampere battery charger. I can't find any terminals that small. Even the #2 stud fork terminals I find are too large.
Now, to figure out what to do. The transformer has no solder lugs. The sockets are part of the molded transformer base, not much chance of digging around and getting a good piece of metal to solder to.
I'm tempted to try to pry apart the crimp on the terminal I have, re-strip the wire, and then form the "crimp" back and solder. Sometimes that works, sometimes, it breaks. I've seen nothing, after several days of searching, off and on, anything like the tiny terminals that this thing uses.