As far as I know I've done all you said.
Put the Supremeinstall file and the Allworlds file in my external hard drive.
Unzipped the Allworlds file. And then dragged it into the Supremeinstall file.
And it's still only the original worlds and about 30 extra worlds that were available in the Spismall in the standard game anyway.
Have noticed though that all the additional worlds end with the suffix .dlw and when I try to import them individually it says it can't open without me stating what I want to open them with.
Don't know if I'll ever solve this one my friend