Lobbying is talking to congressmen, which isn't corrupt at all.
What is the $21.2 million figure for?
That money is not given to the congresmen.
Not directly. It is given to all their friends. Their friends have helped them get elected and will again in future. Direct corruption is only used when you want to blackmail someone.
Paying contractors to lobby for them.
Lobbying is organised persuasion of officials. Corruption is - at its simplest - paying officials.
But organised persuasion can be expensive when you hire the best lobbyists (they are basically sales guys) and they will live in Trump Tower etc...
Lol, something tells me these guys won't be anywhere near Trump Tower.