What bike did you install on? I had a very easy time of it a couple weeks ago on my 2024 Sprint 150s. Recently also installed the rear Bitubo, also with no problem. I used ball-end allens with an extension but didn't even have to bend the angle much at all.
The hardest part for me has been setting the static/rider sag appropriately. I'm starting to realize that the spring is for riders weighing 150 lbs+ but I only weigh 135. I've written to Bitubo about this issue asking if they offer a different spring rated for lighter riders but they haven't responded. For now I'm just going by "feel" as I'm pretty sure just about everybody does anyway.
Every video says you need two people to measure and set the sag but I beg to differ: