In 2014, Siaj began attending
Pfeiffer University in the United States, where he played for the
men's soccer team. He scored his first goal in his debut on 5 September 2014 against the
Millersville Marauders. He was named the
Conference Carolinas Men's Soccer Player of the Week for the first time in Week 4 of his freshman season. At the end of his freshman season, he was named to the All-State Second Team and the All-Conference Second Team. In his sophomore season, he was named the
Conference Carolinas Men's Soccer Player of the Week twice, the National Player of the Week once, and was a selection for First Team All-Region, All-State First Team, and was an All-American Honorable Mention. He scored the overtime winning goal in the semi-finals to advance to the National Championship, where Pfeiffer won the NCAA Division II national title. On 15 October 2016, he scored a hat trick in a 4-0 victory over the
King Tornado. In his junior season, he was a two time Conference Carolinas Player of the Week, was named First Team All-Conference, Second Team All-America, First Team All-State, and First Team All-Region. He left the school after his junior season to turn professional, becoming the school's first ever player selected in the
MLS SuperDraft. Siaj made a total of 69 appearances, scoring 47 goals and tallying 28 assists in his time at Pfeiffer. ==Club career==