Except they were careful and never actually said "we will give you money to vote for Harris/against Trump". Paying you to call him a human toilet isn't against that law.
They were very careful in how they worded the request. They are not asking for people to change their voting behavior, only to create a plan, and to make some public statements.
Obviously, the latter part is fine but the voting plan doesn't require that someone actually change their behavior. They are definitely skirting the line, but I'm sure they had the help of a lawyer when they made this.