On 21 August 2020, Olsen joined Superettan team GAIS for the remainder of the 2020 season.

[5] Later that month, it was also revealed that Olsen had been named Mjøndalen 2024 Player of the Year by the newspaper Drammens Tidende, scoring seven goals and two assists in 27 league games.

[6] On January 19, 2025, it was confirmed that Olsen returned to Denmark, where he had signed with Danish 1st Division club Kolding IF.

[7] He made his Faroe Islands national football team debut on 7 June 2019 in a Euro 2020 qualifier against Spain, as an 86th-minute substitute for Árni Frederiksberg.

[9] He scored his first goal for the Faroe Islands national team on 25 March 2021 in a 1-1 draw in the 2022 FIFA World Cup qualification against Moldova.