In 2016, he completed a Bachelor’s degree in composition at the Royal College of Music, Stockholm, where he studied with Per Mårtensson and Pär Lindgren. He has also participated in master classes with Kaija Saariaho, Johannes Schöllhorn, Simon Steen-Andersen, simone Movio, Eivind Buene, Nicolas Tzortzis, among others. Frej’s music has been performed by ensembles such as Norrköping Symphony Orchestra, OU Symphony, Norrbotten NEO, the Swedish Wind Symphony, Ensemble Suono Giallo, KMH Symphony Orchestra and Musica Vitae in Sweden, Norway, Denmark, France, Switzerland, Italy, Ukraine, and the USA.