Mocyunas attended University High School, where he was named West Virginia Midfielder of the Year, First Team All-State and helped the team to runner-up in the state tournament. He also played club soccer for Arsenal FC of Pittsburgh for three seasons and was named Player of the Year.[1][2][3]
In 2017, Mocyunas attended Marshall University to play college soccer. Here he stayed until 2022 due to a redshirted freshman season and the COVID-19 pandemic that delayed the 2020 season. Over his college career, Mocyunas made 92 appearances for the Thundering Herd and scored a single goal. In his junior year, he helped the team to be College Cup National Champions, also earning United Soccer Coaches Scholar All-Region honors and Second Team All-Conference USA honors.[1][4][5][6][7]