The only thing you need to connect to the RSR plumbing is the fitting in your post from the other day and the RSR union that came with your reefer.
As has been mentioned before- unscrew the barbed nipple and use the 3/4 inch to slip fitting with 15 or so wraps of plumbers tape.
His list of supplies pertains to his particular manifold NOT how to connect to the reefer plumbing.
Depending on your sump space and manifold plans you will have specific plumbing fixtures and needs.
Thanks, I got it plumbed. May be a slow leak from the Red Sea threaded downpipe but I'll get it sorted. I'm looking to order sand and was inquiring about the sand that was used in the current photo. Thanks!