Complex sentence: The club was founded in 1964, however they were first introduced in 1965 when, for reasons unknown, they played in the 3rd division reserve league and its reserve side played in the 4th division.
Split into simpler sentences: The club was first founded in 1964, however they were forced to wait a year in order to play in the 1965 season. For reasons unknown, they played in the 3rd division reserve league and their reserve side played in the 4th division.