Owned and rented simply means you owned a home for some part of the year and ALSO rented some other place for the remainder of the year ... so you say you owned your home for 6 months. What did you do for the other 6 months ? Did you own something else or pay rent ?
You select "Owned."
(The note that is confusing you is related to the question on line 2 of Form NYC-208: "Did you occupy the same residence for at least six months during 2018?" But don't worry about it. Just select "Owned.")