Allow me my pedantry for a minute.

AMS is most commonly felt above 8k feet. Machu Picchu is lower than that. Not saying it's impossible as some people are more sensitive, but if someone is mountain fit...they can handle that I'd imagine.

I have climbed a few mountains higher than that from sea level living in the PNW, so I have an idea of what I'm talking about. Also elevation is elevation. Also, just Google it and you'll see it's 50/50 for untrained people.

It was a 2 day excursion so no doubt it's brutal regardless of fitness but AMS is a specific thing. General exertion/dehydration is more likely here