So can my family see the inside of buildings with a donation or does their have to be a special event? Not clear to me

Yes most all the buildings will be open during 1st Saturday events.

As far as I have seen they only open the buildings during special events

The way im reading it they are closed under normal comditions but if you look on their website for their special events throughout the year then they are open

June 2nd

So on June 2, the buildings will be open to see? "1st Saturdays Events"