This conclusion may be in the form of a reasonable assurance conclusion – ie an opinion is expressed, or may be in the form of a negative assurance conclusion – ie no opinion is expressed.
Is it a typo or misstatement? negative = no opinion?
It’s referring to a reasonable assurance conclusion as an opinion … “In our opinion ….”
For limited assurance the conclusion is expressed as a statement (of fact) – it it not an opinion – see page 9 of the notes: “… nothing has come to our attention …”