Activation Lock

I had brought a iPhone 5s a while ago. When I had brought it, the activation lock was blocking me from getting into the phone. I want to know how to get past it. I tried reaching out to the previous and never gotten an answer. I don’t know the apple id or the password to the activation lock. I need to know how to either get into the phone without needing that info or I need to know how to link my icloud with this phone in order to get into the phone.