Cotter coached the club from 2006 to 2014, winning the Top 14 title in 2009-10 and finishing runner-up on three occasions. During his last season, the club suffered its first home loss in 77 games, a streak that began in the 2009-10 season.
Plummer told Midi Olympique that before he left for Clermont, Cotter explained what he could expect at his new club.
"He explained how incredible the enthusiasm was here and the history of the side. He told me to embrace the culture of the club which has a reputation for being hard working. It won't be easy, I know, but I'm eager to learn."
Plummer won't lack support from the southern hemisphere in the side. Former Blues five-eighths George Moala is in the side while others are Alex Newsome, Irae Simone and Rob Simmons.
After his first training session, Plummer said he arrived at the start of the month.
"The first thing that struck me was the massive support from the fans. It's incredible that so many people turn out on a Tuesday in the summer just to come and see us. It's exciting, and the language, culture and rugby are a massive challenge for me.
"Today's session was very tough. It was quite hot, but you have to go through it to perform well. I'm in a good team and that's the most important thing.
"All pre-seasons are physically difficult, it can often be hot, and this one, my first in Clermont was certainly that. The season will be very long so the trainers are doing what is necessary to ensure we are in good shape and that suits me."
Plummer worked on his French before leaving New Zealand, but being on the ground has shown him how different it is.
"I have to learn quickly because of my position where I have to communicate a lot, but also to understand meetings or video sessions. But I'm not worried about that, the players and staff are great with me."
The Top 14 is a different competition to Super Rugby Pacific, but Plummer is ready for that.
"The physical side of it will be key. I could see that from this first day of the off season with a lot of physical exercises, especially with impressive forwards. But I like that."