In 2018, Costanzo played for Croydon's senior squad where he made his senior league debut against Para Hills Knights. He left to rejoin Adelaide United for a year until being released and rejoining Croydon in 2020. He became the league's second top goalscorer only losing to Adelaide Comets captain and former A-League Men player Allan Welsh. His impressive form would earn him interest from A-League clubs and, ultimately, sign a scholarship deal with Adelaide United at the conclusion of the season.
Marconi Stallions
After being released, Costanzo went on trial with Newcastle Jets and soon after, rejoinedCroydon for a third time before moving to NSW. On 23 February 2022, Costanzo was announced to have signed with Marconi Stallions following in the footsteps of his father who joined the Stallions in the early 2000s.