Yes you need the correct impedance loading the C.T. Then you need a high input impedance RMS calibrated precision rectifier to convert the signal to a dc level for input to your ADC. I have a copy of the op amp cookbook (about 1974 vintage) that I use for a starting point on circuit theory. You will need to search the web for a design that meets your requirements then tailor it for your required specifications. Then you must layout and construct a board that works correctly in the real world.
Seems easier to source the part as a complete subsystem as recomended earlier in the thread (or perhaps in an earlier thread on the topic). Terry