Which campaign deserved surveillance?

This is a good timeline of the sorry affair of the Carter Page surveillance and its background.  This part jumped out at me:

[By October 2016,] the FBI is aware that the Hillary campaign paid lawyers to give money to Fusion GPS, who gave money to a foreign agent (Christopher Steele), who got information from Russian informants. Yet, the FBI counter intelligence effort was being run on the Trump campaign not the Clinton campaign.