From info on the developer's website, I see that Blocks 1,3 &4 in Don Juan II have 4 and 6 apartments per floor while Blocks 2 & 5 have 2 and 4 apartments per floor. The floors are named from the ground up as follows: Semibasement (Semisotano), Ground floor, first floor, second and third floors, and Penthouse, in other words in Blocks 1,3 &4 there are 6 floors in all. Underneath the Semibasement floor is, of course, the Garage. It is clear from the images on the site that the semibasement or lowest floor has 4 apartments A,B,C,& D while the next floor up (Ground floor) has 6 apartments A,B,C,D,E,F. The first, second and third floors have 4 apartments and there are 2 pentouse apartments on the top floor.
Therefore to identify your apartment you need to know exactly which floor you are talking about because in this case Apartment D is the corner one on the semibasement floor but not on the first floor! Your solicitor will be able to ascertain this from the original contract. In my own case I asked for a English translation of the contract in order to check this matter.
The developers website link is as follows:
Hope this is some help to you Richard and Paula.