Your subwoofer has an amplifier built in so you if your receiver doesn't have an RCA sub out you will need a speaker to line level converter such as this
http
/www.mcmelectronics.com/product/60-10385&scode=GS401&CAWELAID=1248439642?catargetid=1545764029&cagpspn=pla&gclid=CKzE1rmwwbkCFRQOOgodwRcAwA