So it turns out that is an input only for analog audio from a DVD/Bluray player. The receiver only has outputs for a passive sub. For anyone else wondering I'm going to try an rca adapter like this one.
https://www.amazon.com/dp/B08C29VBHL/ref=cm_sw_r_cp_awdb_imm_70ZY8KN39QSYXPE9MQM6?_encoding=UTF8&psc=1
Am I in danger of damaging the sub?