From the article:
"Three days after Donald Trump named his campaign foreign policy team in March 2016, the youngest of the new advisers sent an email to seven campaign officials with the subject line: 'Meeting with Russian Leadership - Including Putin.'
"The adviser, George Papadopoulos, offered to set up 'a meeting between us and the Russian leadership to discuss US-Russia ties under President Trump,' telling them his Russian contacts welcomed the opportunity"
...
"To experts in Russian intelligence gathering, the Papadopoulos chain offers further evidence that Russians were looking for entry points and playing upon connections with lower-level aides to penetrate the 2016 campaign."
But some members of the campaign were concerned and didn't bite.