I don’t doubt what you are saying about Trump giving them access. Do we know how he did that? I guess I’d like to understand how we know if it was legal or not.
It's the other way around. It's not legal unless these people are under an executive branch department or agency, with department heads appointed by the president, and confirmed by the Senate.
These people have not all been vetted, hired, and granted security clearances appropriate to the level of access they've obtained.