Make the system as simple as possible...DIY for a novice engineer like myself, and with a minimal budget.
There are two basic ways to use a kite to harness wind energy.
Use a kite to carry turbines and generators up high and transmit the energy back electrically.
Use a kite as a wing and harness the power transmitted mechanically via tensile force in the lines to the machine that it's attached to.
The latter is simpler if for no other reason than that the part that's flying around is commonly available (kite surfing kites), and the fewer things you need to keep in flight, the simpler.
Within this approach, we need to decide what kind of work the linear force of the kite lines is going to perform. Numerous approaches have been or are still being pursued by from a laddermill, to a carousel, to other notions.
Again, trying to keep things as simple as possible, I strive to emulate the well-proven interaction of kite surfers with large kites. One way to do this is to have the lines wind and unwind a spool.
This might be my software engineer instincts mis-guiding me in hardware-land, but I generally try to divide problems up into subproblems, and that's the approach I'm taking here.
I've designed and built a drive/recoil system that assumes that that kite is attached via a single line around a single spool.
I want to hook the drive/recoil system up to a kite. I can do it via the single line seen in the video attached to something, or I can replace the single line with four kite lines. I've kicked around a number of ideas, and started prototyping a couple, but none seems super promising, so far.