I took a closer look at your modpack.. Seems like you have everything right except the zip file structure, maybe there were some additional settings there that the basic zip extractor cannot parse. I repacked your modapck zip file and the launcher installed your modpack in seconds. I'm using WinRar with the zip setting.
New Dropbox Link:
https://www.dropbox.com/meta_dl/eyJzdWJfcGF0aCI6ICIiLCAidGVzdF9saW5rIjogZmFsc2UsICJzZXJ2ZXIiOiAiZGwuZHJvcGJveHVzZXJjb250ZW50LmNvbSIsICJpdGVtX2lkIjogbnVsbCwgImlzX2RpciI6IGZhbHNlLCAidGtleSI6ICI3ejQ5Y20wNjdmbTFpcDQifQ/AALEAZwB_ipxYVobUzUgESgRP2H92s9cKZVaI2z-xEIauQ?dl=1
What the Technic Platform saves:
https://www.dropbox.com/meta_dl/eyJzdWJfcGF0aCI6ICIiLCAidGVzdF9saW5rIjogZmFsc2UsICJzZXJ2ZXIiOiAiZGwuZHJvcGJveHVzZXJjb250ZW50LmNvbSIsICJpdGVtX2lkIjogbnVsbCwgImlzX2RpciI6IGZhbHNlLCAidGtleSI6ICI3ejQ5Y20wNjdmbTFpcDQifQ/AALEAZwB_ipxYVobUzUgESgRP2H92s9cKZVaI2z-
This is due to the standard length of characters a normal test field/string saves (255 characters).
Since the new dropbox links are longer than 255 characters, it cuts off the rest of the new link.
We are working to fix this issue. Expect a hot fix within the next day or so.
Edit: http://copy.com has been suggested as an alternative.