Need help using Komikku

I'm using Kotatsu right now but it's not the same as i used it before. I try installing this Komikku app and i don't know how to use it -,-; (this is my first time using another app like Kotatsu TT)

They both seem similar but the thing is I can use Kotatsu easily while komikku needs to uhhh i think it says "storage" or "local storage" and i try my best following their guides but its still not working(maybe I'm just dumb ;-;)

Ahemm... I really need some help on how to use komikku :< (oh and uhh sorry for my wrong grammar or whatever it is I'm not good in english ಥ⁠‿⁠ಥ)