How can I apply the Dracula terminal theme?
The theme you got is for the iOS terminal.
You could try to mimic it, though, going to Terminal > Preferences > Profiles > Edit and choose the colors manually to look like the Dracula one.
Or you can use this website Terminal.sexy:
To help you select the colors, and either download an import or manually set your colour palette.
More about it and how: Load theme files in Gnome Terminal on Ubuntu 15.04
Late response, but currently there is a theme for GNOME Terminal (currently used by Ubuntu): https://draculatheme.com/gnome-terminal