Sorry to say this is incorrect - I think you mean if the OP is paying for it themselves (via any payment method, personal credit card, corporate credit card, cash) you can get credits. If the vendor is directly paying then it is not likely you would get any points/night credits as you shouldn't per the T&Cs.

However, this relies on the vendor having booked the Marriott through a direct or "official" channel, unfortunately with some corporate bookings they put you through Egencia (essentially corporate expedia, where you may, or may not, get points credit). There is more on this thread, where your post may be merged: Corporate Travel Portals General Discussion Thread

The confirmation number they've given you is probably from the travel agency, rather than the Bonvoy number. As such, unless you want to make a big deal out of it (i.e. getting them to give you the full booking confirmation with all the numbers to try), I would just give the front desk associate your Marriott details when you check-in, and see if it posts.