well as the title itself explains "arranged employment category" , yes you need an employment letter from your employer which explains that he is giving you a permanent full time job on the basis of the valid LMO you currently have. Basically, its just a kind of permanent job letter which an employer gives to his employee on the basis of the LMO they have. So if you already have LMO, closed work permit, IELTS is done, YOu just need a letter from your employer which describe your permanent job offer.