Career
He has previously played for BK Häcken and Football Club Väsby United and GIF Sundsvall. In August 2013 Holster signed for Azerbaijan Premier League side Ravan Baku. On 19 October 2013, Holster made his debut for Ravan Baku, coming on as a half time substitute for Miloš Adamović in their 2-1 defeat to Neftchi Baku.
Holster left Ravan at the start of the winter break in December 2013, and went on to sign a two-year contract with Assyriska in March 2014.