[1][4] In spite of being strongly linked to AC Milan, Manchester City, Paris Saint-Germain and Juventus in September 2017,[5] he signed a three-year long professional contract with the club on 9 October 2017.
[6] On 12 March 2019, in a UEFA Youth League round of 16 game against Liverpool, he provided Leon Šipoš with an assist for the equalizer.
[8] On 11 December, in another Youth League campaign, he scored the only goal in a 1–0 victory over Manchester City and secured Dinamo's spot in the play-offs.
[11] On 1 October 2020, Marin was sent on a one-year loan to newly-promoted Serie B side Monza, with an option for purchase which becomes an obligation under certain conditions.
[19] In his second appearance for the club on 17 February, he scored a brace against Radomlje in a 3–1 win, but suffered a knee injury and had to undergo surgery.