In 2013, the manager of local amateur side Rhodense [it], Alberto Bianchi, spotted Liberali and invited him to play in a youth tournament with a view to later sign him.[2] However, he would participate at the tournament with Aquile della Brianza from Muggiò instead, spending a year with the side before joining La Dominante, who he would train during the week with, while playing with professional side AC Milan on weekends.[2]
After a year of this arrangement, Liberali made the switch to AC Milan permanent.[2] During the 2021–22 under-16 Scudetto tournament, he finished second-top scorer behind Francesco Camarda with nine goals, as AC Milan went on to win the competition.[2] He was called up to train with the first team for the first time, alongside Camarda and Nirash Perera, in December 2022.[3] The following year, in July 2023, he signed his first professional contract with the club through 2027.[4]
Liberali joined AC Milan for their 2024–25 pre-season, displaying impressive performances during the friendly matches, including the headlining assist for a 1–0 win against Spanish La Liga club Real Madrid at the Soldier Field in Chicago, Illinois, United States, the club's third friendly match on 31 July 2024.[5] He made his professional debut on 10 August 2024, starting for the newly created reserve teamMilan Futuro, and scoring the first goal of a 3–0 away win Coppa Italia Serie C first round match against Lecco.[6]
Initially a central defender while playing at 7-a-side level, Liberali was moved up the pitch in the academy of AC Milan, settling at left-wing, with Italy under-17 coach Massimiliano Favo [it] also utilising him as an attacking midfielder.[2] Former AC Milan defender and current football pundit, Alessandro Costacurta, compared him with English international Phil Foden for their similar playing style.[8]