It’s easy for BNI! Besides needing a comma, there are two mistakes made over and over and over and over again.
The offending (and offensive) sentence:
The process to become an Ambassador starts with exemplary leadership in their chapter, they are nominated by someone on our Team, they go through a number of interviews with our Directors, and finally, they complete the Ambassador Orientation.
The first mistake is incorrect capitalization. “Ambassador,” “Team,” “Directors,” and “Ambassador Orientation”—none of these words or phrases are proper nouns or proper noun phrases. If, for example, the phrase was “BNI Ambassador,” I’d let it slide, because it’d be something unique to BNI. But not “team,” not “directors,” not “chapters,” not “members.” Not ever. Someone once told me that “Capitalizing ‘members’ makes our members feel special.” My reply was, “No, it just makes you look wrong.”
The second mistake is noun-pronoun agreement.  We start out with “an ambassador”; in other words, one ambassador. You just cannot pair a singular noun with a plural pronoun. It. Cannot. Be. Done.
Plus, this is a damn long sentence; too long, in my opinion. But I didn’t count that as a mistake.
Still, nine mistakes in one sentence is nine too many!
They had:
The process to become an Ambassador starts with exemplary leadership in their chapter, they are nominated by someone on our Team, they go through a number of interviews with our Directors, and finally, they complete the Ambassador Orientation.
Corrected:
The process to become an ambassador starts with exemplary leadership in his or her chapter. He or she is nominated by someone on our team, and then the candidates go through a number of interviews with our directors, and, finally, they complete the ambassador orientation.