If you comply in all other respects, you have nothing to be concerned about, but don't take my word for it, check with a CPA. If the first one says no, get another one, seriously. Why would the legislation discriminate against people who buy their first home in a multi-occupancy apartment buildings of more than 4 units, which would also be commercial? Lots of people buy their first home in commercially zoned property. What's the difference? I've been forwarding the link below all day, it's a good explanation of the $8,000 refund and how to apply for it. I don't know this agent personally, but it seems the best explanation I have seen around. And by the way, i see everyone talking about a tax credit, but my understanding is that it's a tax refund, the difference being you get cash in your hand, as opposed to a credit, which just runs as a loss against future income. Big difference.
Just my opinion, yours may differ. Looks like a nice property.