You've had a number of posts in the last day and you keep leaving out the make and model of the equipment you are using. Kind of like saying "I have a car and it is making a noise, how do I fix it?" - Make and model matter a great deal, as well as additional details about the equipment. Please provide them in the first post, that way people won't ask for that information and can help you out more better.
This is your receiver, right?
https://www.crutchfield.com/S-gM6v6QiVcRI/p_580TXN515/Onkyo-TX-NR515.html#&gid=1&pid=2
If so...
Use a RCA cable to connect your Onkyo purple subwoofer conection to the LFE input on the subwoofer.
As long as this is your receiver, then it's just the one connection. Your receiver offers TWO subwoofer outputs, but both of them provide the exact same audio. So, just use one of them and connect to the LFE input of your subwoofer and move the switch to LFE on the subwoofer.