Discovery Player. He made his debut for the club in the opening game of the season against Chicago Fire, playing 76 minutes before being substituted, in a 1–1 draw. After making his debut for Columbus Crew, he found himself rotating in and out of the starting line–up. By August, Abu began to make a start in a number of matches for the club. He helped Columbus Crew qualify for the 2017 MLS Cup Playoffs, where the club reached the Conference Finals, losing 1–0 against Toronto FC on aggregate. In the 2018 season, Abu found his first team opportunities limited at Columbus Crew, due to strong competition. As a result, he found his playing time coming from the substitute bench. In July 2018, Abu suffered a thigh injury that saw him ruled out for months. Vålerenga On 10 August 2018, Abu returned to Norway when he was sent on a season-long loan to Vålerenga. He made his debut for the club, starting the whole game, playing in the defensive midfield position, in a 3–0 win against Tromsø on 19 August 2018. After the match, his debut performance was praised by Vålerenga's captain Daniel Fredheim Holm. After joining the club, Abu quickly established himself in the starting eleven, playing in the defensive midfield position. Despite suffering a knee injury later in the 2018 season, he went on to make eleven appearances in all competitions. During the 2018 season, the deal was made permanent on 4 October 2018. At the end of the 2019 season, Abu went on to make twenty–six appearances in all competitions. Following his loan spell at D.C. United, his contract with the club was terminated on 18 December 2020 and he announced his intention to return to play in America. D.C. United (loan) On 2 March 2020, Abu was transferred to MLS club D.C. United on a one-year loan with a permanent option. However, the season was suspended due to the COVID-19 pandemic in North America, following the cancellation of several matches. He made his debut for the club, coming on as an 87th-minute substitute, in a 0–0 draw against FC Cincinnati on 22 August 2020. During a 2–2 draw against Toronto FC on 19 September 2020, he suffered a knee injury and was substituted at half time. After the match, Abu was ruled out for the rest of the season with a knee injury. At the end of