Kalongo was born in Canada to a South African mother and a Kenyan father.[1] He played youth soccer with the Milton Youth SC.[2] He later joined the youth system of Sigma FC.[3]
In September 2021, he joined Forge FC of the Canadian Premier League on a developmental contract.[5] In February 2022, he signed a standard contract with Forge.[6][7] He made his debut on April 10, 2022, against Pacific FC.[8] He won the CPL title with Forge in 2022.[9] In March 2023, he re-signed with the club for another season.[10] In October of the same year, he was a part of the Forge squad that won their fourth league title, following a 2–1 victory over Cavalry FC in the play-off final.[11] In his first three seasons with the club, he made just three appearances, serving as the backup goalkeeper,[12] however, after Triston Henry did not return to join the squad for the 2024 season, Kalongo began the 2024 season as the team's starting goalkeeper.[13][14] He was named the Canadian Premier League Goalkeeper of the Month in April 2024.[15][16]