She played a backup role for the Florida State's 2021 national championship team before transferring to Texas, which she led to both Big 12 and SEC titles.

She kept five clean sheets in her eight starts in the 2021 season, being named to the Atlantic Coast Conference all-freshman team.

[2][7][8] With the program's move to the Southeastern Conference in 2024, Justus kept a program-record 12 clean sheets and was named to the All-SEC third team.

She led the Longhorns to the SEC championship as the tournament's most valuable player, posting a career-high 14 saves in a 2–1 win against Arkansas in the semifinals.

[16] She started two games at the 2022 FIFA U-20 Women's World Cup, but the team did not make it out of the group stage.