I'm not 100% sure that what you want is possible - certainly not with the cord that you linked. That one is designed to link an Ikelite housing to a Sea & Sea strobe, while what you need is the reverse - a cord to link a Nikonon / Sea & Sea type housing to an Ikelite strobe. At first glance, this should be suitable, but alas, Ikelite remark right there that Meikon has fitted their housings with a non-standard Nikonos-type bulkhead, which is not compatible with this cable.I don't have that housing myself, but another poster has remarked that the sync connector on Meikon A7R II housing only has two wires - this may have something to do with it.
Your least expensive option is probably to sell the DS-51 and buy a used Z-240 or YS-D1, or a new Meikon ST-100, plus Meikon's sync cord for Inon/Sea & Sea strobes. Failing that, you can look for a used Ikelite housing for your camera, plus an Ikelite-to-Ikelite cord to connect your strobe.