Three different authorities say three different things, and the one that controls your financing is the city license.
A lender underwriting residential multifamily needs rooms to be legal conforming units, which typically means a certificate of occupancy or at minimum a use permit matching the rent roll. Eight rooms on a T12 with a six-unit license reads as two units of unpermitted income, and most conventional lenders will either haircut those two rooms to zero or decline the file. Say gross rents are $800 per room: the lender may underwrite $4,800 instead of $6,400, which shifts your cap rate and your maximum loan amount materially before you negotiate anything.
The floor plan count being seven, not six or eight, is the detail nobody above flagged: that middle number suggests someone added a room inside the structure without pulling a permit, which is a different problem from simply renting more rooms than the license allows. An unpermitted room addition touches habitability, egress and potentially fire code, all of which a city inspector can order remediated at your cost after close.
What lenders will actually do with the income depends on whether they classify the property as residential or transient lodging. Rooming houses in Arizona can fall under either, and if the city treats it as a lodging establishment rather than residential rental, your financing options shift to commercial or portfolio loans with different coverage requirements.
Has the owner pulled any permits in the last five years, or is the city license the only paper trail you have?