Grant funds for the development of one's own business

I was allocated grant funds for my own business, now I started to spend them, and at the bank (Oschadbank) an employee said that a mandatory condition after receiving a grant is to use only their bank, that is, opening a FOP account, drawing up a salary project, and paying taxes ONLY through their bank. If I do not comply with all these conditions, then the funds must be returned, since these "mandatory" conditions were not fulfilled. I wonder if this is true? what should I rely on in the opposite case?