Yeah, that's a pretty sticky part. Venus has appx earth gravity and atmosphere at that point, so you'd need an Earth-class launcher to get off; something at least like an Atlas or Titan II. The launcher itself we could get there reasonably, but the propellant, well... that's an awful lot of mass to send to Venus. It gets much easier if you can do ISRU, which may be easier on Venus, but is still a novel development project.

EDIT: after further reading the article...

In the article it shows that most of the payload (60k kg out of the 70k kg payload) of the airship module is the ascent vehicle. Each of the two transit modules is launched by what looks like 4 Delta IVs and one SLS Block2--each. (Plus two crew capsule launches at each end of the mission for Earth departure and return.) So I guess they have some mass to work with. Heck of a launch schedule.

That 60k kg ascent rocket is just a bit bigger than the Pegasus XL, which can launch 443 kg. A Mercury capsule is 1200kg. Granted the ascent capsule doesn't need a heat shield, but that's not a lot of rocket for two people.

You did - there's a rocket ship attached to the bottom of the airship (accounting for 6/7ths of the mass of the airship IIRC).