Can't connect LINE account to "Tsum Tsum" Game

I’ve been playing this game for a bit and I got pretty far. However, if I deleted my game my mom and I would be a goner. I’ve been trying everything to connect line account but nothing works. I also tried to use Android and my mom had to restart her whole game before she could link her line account and I don’t want that. Can anyone help me? Thanks!

PS: This is not from five years ago because the only things I got to read were from 2-6 years ago this is from 2020