I know you can do a “b stance” RDL instead of trying to balance on one leg and it targets the same muscle groups this exercise does. That’s what I do

if u can't balance ik this sounds weird but spread you toes, it like naturally locks your ankle making u less wobbly

slowly getting better at this. I can feel it either side of my lower back rather than in my legs though.

This is with me too. It is difficult and my lower back also hurts. I don’t know what’s wrong am doing.

Try shifting your weight towards the leg that’s standing and not being pushed backwards. It takes some getting used to but you’ll get it.