Im having the same problem (we meet again miniboxer XD) and I think this may be an error with dropbox, not sure though. I've definitely confirmed that its a problem with the zip file not downloading at all. I have evidence, if you go to .technic, then the name of your modpack, you can see that in the temp folder there is the zip in which the files you uploaded to dropbox would be, but only 1 kb in size. My conclusion is that the download is starting, and the zip is created, but its not downloading for some reason, the fix, thats what I'm here for. As a last note, if you open the incomplete zip, it will tell you that it is corrupt or incomplete.