Cancar was born April 10, 1997 in Koper, Slovenia. Six days after his 18th birthday, he signed his first pro contract -- a five-year deal with KK Olimpija of the Slovenian league. He left for the Adriatic League after one season and was selected by the Nuggets the following summer in the 2017 NBA Draft. He stayed in Europe and helped Slovenia to a gold medal in EuroBasket 2017, defeating Turkey in the finals. After two more seasons in Spain, Cancar made his way to the United States to sign his rookie deal with Denver.