The 50-year-old this week returned to the club he guided to the 2009/10 Eredivisie title three months after stepping down as Nottingham Forest manager following a frustrating spell at the City Ground.
McClaren told TalkSPORT: "I know the club very well. I know the people, I know the fans, I know the team and it's coming back into an environment in which I know.
"I came back because of the ambition of the people, the ambition of the club.
"It was a good opportunity at Forest, but I wasn't given the tools to do the job. I was not given what I was promised, so that was unfortunate that I had to leave there.
"I was just waiting for an opportunity with ambitious people. I know the people I'm going to work with and I see a team that I can develop.
"Anybody who saw the team against Fulham [in the Europa League] will testify they are a very good team, and they are one of four teams who can win the Dutch title."
