From the article the turbine unit weighs 2204lbs so that’s ~9400 lbs total. Omni calculator says you need 348,436 standard 11" party balloons or 3,979,252 litres of helium to get off the ground and 423,779 party balloons to reach 1.5km altitude.
2"Ø UHMWPE rope has a breaking strength of ~375000lbs weighs 94lbs per 100’ so about 4700lbs for 5000’
That said I have know idea if 2"Ø is the correct diameter rope to anchor one of these balloons.
edit: I was originally planning on adding in the weight of a high voltage transmission cable, but I’m on my phone and feeling lazy, maybe some one else will feel more inspired than I.
I’m assuming that’s the weight of the turbine without helium in the balloon.