It was Klopp's first major appearance at the stadium since he left the club 18 months ago.
He said: "When I left here I didn't know how often I would come back. First year I didn't want to jinx it (Liverpool's Premier League title triumph), now I didn't want to create wrong expectations or whatever.
"There's always a reason not to, but this was great. There was no doubt that I had to come to support the foundation, and that's why we are here.
"And the nice thing is that we play a game at Anfield against my other old club, which is really nice."
He added: "It's just nice, being here, having absolutely no pressure, no intensity, just here to enjoy the atmosphere and I can't wait.
"More than 60,000 people here this afternoon which is completely ridiculous. And I hope the players can entertain in a different way, a little bit."
The charity match between Liverpool Legends and Borussia Dortmund Legends ended 2-2.