Got interview for 16-month co-op but I can only do 4-8 months — how to handle this?

I’m a finance student in Canada and just got invited to interview for a 16-month co-op (corporate finance / financial analyst type role).

The issue is I can only realistically do 4-8 months without pushing graduation back significantly (Coop student going into 5th year, if I were to graduate in 6 years I feel that'd be a bad look, maybe someone can give some perspective on this?). I can’t commit to the full 16 months unless I delay school more than I’m comfortable with.

I don’t want to waste their time, but I also don’t want to disqualify myself before even interviewing.

Would appreciate advice from anyone.