In 2021, Manning joined the coaching staff of his former Kansas teammate
Mark Turgeon at
Maryland. After Turgeon stepped down as head coach on December 2, 2021, Manning was named Interim Head Coach. Maryland finished the season 15-17 with seven quad 1 & 2 wins, four top 25 wins after playing 18 games vs teams in the 2022 NCAA Tournament. Maryland finished first in the Big Ten in both free throws made (456) and free throw percentage (.760), while ranking third in free throws attempted (600). The Terrapins were 13-1 when leading with 5:00 minutes to play, with its one loss of the season coming at No. 3 Purdue. They were also 10-4 when out-rebounding their opponent on the season.