Comprehension question regarding KfW funding "First-time purchase of residential buildings"

Thank you.
It is the case that the KfW is currently checking with me whether the confirmation after completion (from the energy consultant) is correct and whether I will receive the repayment grant. Since I bought apartments for rental purposes 10 years ago, I am afraid that the initial purchase might not be applicable because of that. However, it seems that for the KfW 55 funding it does not matter whether one was already an owner of residential properties before.