So what was the exact plan and who were involved?

It would have been easier to kidnap the guy some other way and not risk him dying. And why would they target him? THey would not know he was a bone marrow match. And it was clear from the ending, this had nothing to do with revenge by Machete. Was the zipline operator involved? Someone had to give him that frayed belt.
Or was the whole thing an honest accident and at the hospital , they screen everyone for that bone marrow match, and once they find one, they proceed to cover up by paying everyone from the ambulance guys to the front desk lady and then notified the gangster that this guy was a match.

And if the ambulance guys were in from the beginning, why would they give the correct hospital card and how would they know that she would have a crash delaying her.

But then again, if the whole thing was an honest accident, why would the zip line guide lie about the name of the zip line operation and not tell the owner. Or was the owner paid off too after the fact.

I enjoyed the movie, but it is a shame that your typical movie writer lacks basic command of logic.