It was Trump Jr and Paul Manafort, the Trump campaign manager.
Robert Mueller investigated the incident for the Justice dept. He concluded Jr. was to dumb to know what he was doing. This isn’t plausible because he had Manafort advising him.
They called someone during the meeting, probably Donnie Sr, but it hasn’t been proved.
Manafort was convicted on charges but I don’t think they were related to this incident.
Mueller obviously intended to never prosecute anyone in the Trump family.