English loves to confuse its learners with words that seem to contradict logic.
If I am indisposed, it means I am sick, ill, off-colour. I’ll probably be staying at home and possibly in bed. It is a formal and somewhat old-fashioned word used for effect or as a euphemism.
The boss is indisposed today. He had a heavy night with his golfing partners.
If you don’t want to do something or feel negative towards a person or a project, you can say you are ill-disposed. It has nothing to do with health.
Susan seems very ill-disposed to working with Marina. Oh, didn’t you know? Marina is dating Sue’s ex.
The manager was ill-disposed towards Eric because he felt that Eric’s department was not producing enough results.