Hein began playing football with the youth academy of Thionville at the age of 4.[2] He joined the youth academy of Metz at the age of 12, and worked his way up their youth teams and reserves.[3]
On 23 May 2019, he signed his first professional contract with Metz, keeping him at the club until 2019.[4] He signed on loan with Tours for the 2017–18 season.[5] He then returned to Metz for the 2018–19 season, extending his contract by one more season until 2020.[6] For the 2019–20 season, he joined Valenciennes on loan.[7]
On 26 June 2020, Hein transferred to Auxerre, signing a three-year contract.[8] He was one of the nominees for the 2021 FIFA Puskás Award, for a goal he scored against Niort.[9]
Personal life
Hein was a national champion in table tennis in his age group at the age of 12, and at 13 had to decide between pursuing football or tennis professionally.[10]