In the linked article, a 22-year FBI agent experienced with court and surveillance explains how the FISA process usually works to ensure that none of this happens but draws inevitable conclusions of why it did happen with Crossfire Hurricane.
The wiretapping abuses in Operation Crossfire Hurricane are far worse than Watergate because they involve, not just a corrupt president (Obama) ordering it, a corrupt candidate (Hillary) fabricating a fake dossier to get the wiretaps, but a complete corruption of the Attorney General (Lynch) and the head of the FBI (Comey) for authorising and overseeing it, the corruption of virtually everyone involved with it in any way in any of these departments, and furthermore, the corruption of the FISA court itself for not conducting the proper oversight and checks.
What is still most amazing about all of this is that after wiretapping Trump's campaign for eleven months, not to mention the two-year long Mueller investigation, they still couldn't come up with a single indictable offence against him.
Remember the umbrage in March 2017 when the president said that he had been “wiretapped” before the election? Then-FBI Director James Comey testified he had had “no information” to support that idea, and he had “looked carefully inside the FBI."
Former Director of National Intelligence James Clapper said there was no surveillance, and as DNI he would have known about a court order on "something like this." PolitiFact labeled the claim 100% false.
What a difference a year makes. Recent revelations of the extent of the anti-Trump surveillance activity have forced Trump critics to adopt a new narrative. Clapper now says spying on the campaign was actually a good thing. The New York Times took issue with the term “spying,” saying rather that it was simply an “investigation.” This dickering over terms is reminiscent of when former Attorney General Loretta Lynch insisted the “investigation” into Hillary Clinton’s home-brew email server be called a “matter.”