Answer by taking a quote from the following article:

Martin Sandberg (born 26 February 1971), known professionally as Max Martin, is a Swedish songwriter, record producer and singer. He rose to prominence in the second half of the 1990s after making a string of major hits for artists such as the Backstreet Boys, Britney Spears and NSYNC. Some of his earlier hits include "...Baby One More Time" (1998)

"I didn't even know what a producer did, I spent two years-day and night-in that studio trying to learn what the hell was going on." - Max Martin, 19 March 2001.  In 1993, Martin was hired by Cheiron Studios and spent some time learning the basics, before the first production collaboration between PoP and Martin: the Rednex song "Wish You Were Here" in 1994. They both worked on Ace of Base's second album, The Bridge (1995), shortly thereafter, as well as on albums by 3T, Army of Lovers and Leila K. To date, The Bridge has sold more than six million copies worldwide, including one million in the United States. When Martin eventually left his band It's Alive in late 1995, he was replaced by Anders Jansson.  In 1995, the Cheiron Studios was hired by Zomba to work on Backstreet Boys' self-titled debut album Backstreet Boys (1996). Zomba became the main working partner since the success in 1995. Martin took part in the production of "Quit Playing Games (With My Heart)" (1996), co-written with Herbie Crichlow, a single which quickly went platinum and climbed to No. 2 on the Billboard Hot 100, as well as the singles "As Long As You Love Me" (1997) and "Everybody (Backstreet's Back)" (1997). The album was not released in the U.S. until 1997, but was released overseas and caught on all across Europe, eventually selling around 8 million copies worldwide. This led to the Backstreet Boys being relaunched in their home country later on, this time more successfully. Later that year, Martin co-wrote and co-produced Robyn's hits "Show Me Love" and "Do You Know (What It Takes)" which ended up on the Billboard Hot 100 top 10.  In 1998, Cheiron Productions worked on albums by Five and Jessica Folcker. Jessica Folcker had first been hired as a backing singer for tracks with Ace of Base and Dr. Alban, and her debut album Jessica became an instant hit with singles like "Tell Me What You Like" and "How Will I Know Who You Are" which both sold platinum. After Denniz PoP died of cancer that same summer, Martin took over as director of Cheiron Studios. He soon started working with writer/producer Rami Yacoub, who continued to be his partner for many years. Martin also wrote two songs with Bryan Adams during this time, "Cloud Number Nine" and "Before The Night Is Over."

Is there any interesting facts about Max Martin working with Cheiron and Denniz PoP?
the Cheiron Studios was hired by Zomba to work on Backstreet Boys' self-titled debut album Backstreet Boys (1996).