From about the 1960s to sometime in the 1980s or so, UAG was the prime non-US destination for US students not accepted to medical school. Sudents didn't desert it because it wasn't providing a good medical education, but because of the proliferation of English language Caribbean medical schools. Guad has has lots of graduates in US practice. You will have to learn Spanish, if you don't already know the language. And if you don't, learning it is a good idea. It is now the second language in the US.
Mexican medical students complete the medical education, but do not earn the medical degree until after completing two years of "social service", working as physicians in, usually, underserved Mexican communities. Since not having the medical degree after four years of study and leaving Mexico posed licensing problems for US graduates, several US medical schools developed something called "fifth pathway" programs, eventually permitting licensure. Since the large drop off in students going to Mexico, these programs have greatly diminished; Guad can tell you what ones may be available. Mt. Sinai in New York City may still have one.
Guad has a US office, in Texas I believe, but I don't have the address. Ask Guad for it; it is probably also in its brochures.
Guad always has a presence at meetings of the national association of premedical advisors. If you have a premed advisor, inquire there.