[3] On March 7, 2020, a day after signing with Union II, McGlynn made his competitive debut for the side in the USL Championship against Loudoun United.
[2] He made his debut for the Union on April 14, 2021, in a 4–0 victory over Deportivo Saprissa in the CONCACAF Champions League, coming on as a 68th-minute substitute for Leon Flach.
[7] McGlynn's debut in Major League Soccer came on April 24 against Inter Miami, coming on as a late substitute for Ilsinho.
Philadelphia would also retain a sell-on percentage of any future transfer, as well as potentially receiving a further $1.3 million if certain performance-based metrics are met.
[12] On October 8, 2023, McGlynn was called up to the United States under-23 national team ahead of friendlies against Mexico and Japan.