This easily wasted an hour of my time. And made me ill thinking I was about to break our new sink just before I finished installing it. Hopefully helps a few other people.
Here is the owner’s manual for the UberHaus 80375034 Kitchen Faucet, on the subject of the “Hose Adapter”…
…and here is what the Hose Adapter looks like once it has connected, and once you have heard the “click” sound…
Such a satisfying conclusion required the removal of this plastic cap from the top end of the hose adapter…
…why they don’t mention that cap in the manual I have no idea. Felt like I was about to break something when I was pulling out the cap with pliers. It looks like part of the adapter.
Obviously, I’m not a plumber.