Yes, of course, it is the Mass that matters, not the building. In the early times, the Holy Mass could be celebrated even in the woods, in the open air, in a basement, or in a rented room, even in a space like one above a supermarket. What matters is that the place should be, more or less, a worthy environment. It should be arranged with a sense of reverence.
The space can then be decorated with Catholic items and symbols to reflect the sacredness of the celebration. What truly matters is the Holy Mass itself.