Out of curiosity, just went to the Spanish embassy / VAC page, appears that they use the same appointment reservation system as does my own country but for passport renewals. Yes, that system (VFSGlobal) is a piece of s**t. A couple of weeks ago I had to make appointments to renew the kids passports and even the official admitted that it does not matter what I enter in the system, just need to have a booking number, period. That's what I did.Spanish embassies in general are a pita to deal with. Not sure if they have the same system in the DR but here you have to make an appointment online (which is difficult) and they don’t let you in if you didn’t. As for flights AirEuropa has cheap direct flights between SDQ and Madrid.
But obviously, if you have no appointment, they would not let you in... I just consider this one of those things one has to put up with dealing with the/any govt...