Edit: I realized that you can't change pages via the physical buttons on the kobo forma if you just opened Ultimate Manga Reader and then you pick a Manga from the favorites section straight up.
To be able to make the physical buttons work you need to go pick any manga from anywhere execpt favorites section and then change the pages with the physical buttons.
If you go back to the favorites section you will be able to change the pages with the physical buttons but everytime you close than reopen Ultimate Manga Reader you will have to do it again.
Edit: I realized that you can't change pages via the physical buttons on the kobo forma if you just opened Ultimate Manga Reader and then you pick a Manga from the favorites section straight up.
To be able to make the physical buttons work you need to go pick any manga from anywhere execpt favorites section and then change the pages with the physical buttons.
If you go back to the favorites section you will be able to change the pages with the physical buttons but everytime you close than reopen Ultimate Manga Reader you will have to do it again.