Question about a verse in Coran

Assalam Alaikum W.W. My name is Hamza and I am trying to grow my knowledge in islam in order insh'allah to increase my iman and explain to others the authenticity of our religion. Here is a question I ve got from a brother on internet: sourat 23, verse 5 to 7 it says: And who guard their modesty Save from their wives or the ( slaves ) that their right hands possess , for then they are not blameworthy. Briefly, In islam we are only allowed to have sexual relation with wemen to whom we are married. So if you take your slave when in fact you're not islamically married to her, isn't committing adultery. Please Brothers, you probably have a better knowledge then I do. If you have an answer to this question, may Allah give you the courage to share it with us and sprend his blessings on you. I have one last verse to clarify, but I will send it to you in the coming days insh'Allah.