In the summer of 2018 Flatla made her debut in the Grand Prix in Planica . There he was able to win points in both competitions. In the winter of 2018/19, however, he only competed in four Continental Cup competitions and the 2019 Junior World Championships in Lahti and otherwise stayed away from international competitions. In Lahti he reached ninth place in the sprint and also won the silver medal with the team together with Aleksander Skoglund , Jens Lurås Oftebro and Andreas Skoglund .
In the summer of 2019 Flatla reached the points in the Grand Prix twice. With a total of fourteen points, he finished the summer in 54th place. At the beginning of December 2019 Flatla was part of the national group at the home World Cup in Lillehammer . On his debut, he made a strong jump, so that he went on the trail in ninth place and ultimately crossed the finish line in 19th place. On the second day of the competition, Flatla also achieved top distances in jumping, which again laid the foundation for his nine points. Because of these achievements Flatla stayed in the Norwegian World Cup team in the following weeks. In March 2020 Flatla reached the podium in the Continental Cup for the first time in Lahti behind Jakob Lange . He finished 39th in the overall World Cup ranking.