However, a transmitter with enough power to signal earth would be too massive to get fast with a solar sail, given today's technology. Maybe a chipsat gets to 20% c, but no way a dish does.
so it looks like they'd want to launch by 2036. In the 'technical challenges' section, it does mention that some technologies would have to be miniaturized sufficiently, but it doesnt really mention much about whether that technology has reached viable stages or not, or whether it's a realm they'd have to specifically research further.
So I guess maybe the technology doesn't exist today? Sounds like probably not, but maybe the near future -- or at least they expect it to exist by 2036.
It's worth noting this project has backing by some pretty influential folks, including Stephen Hawking when he was still alive.
So that the signal can be relayed by a bunch of short range transmitters all the way back to earth