The building has 4 entrances to 4 separate two-storey-apartments. The apartment in question has two names: 901 and Villa Vicaria. I don't think that the name of one of four apartments should be tagged onto the building.
Postal address is probably 901 (or 85 901).

Building 901 does have a name (Villa La Vicaria) which is no part of its postal address probably. That's why addr:housenumber seemed to be more appropriate.
The general situation in the building complex is difficult. Originally the buildings were named 85-XXX (85 for whole building site). Some are still named that way, over time others used the three-digit numbers only. I decided to tag according to actual naming use.

(Situation as of October 2021)