Thanks David! That did the trick.

One thing for any other newbies who may read this thread- when setting the path for the Xcode (MacOSX) >> VST (Legacy) SDK Folder, it was easier to click the "..." browser button, rather than typing the address (which I kept getting wrong.) That's what led me to see that file path needed to be written as:
../../tools/SDK/VST3 SDK
rather than:
HISE-master/tools/SDK/VST3 SDK

Also, Xcode annoyingly keeps displaying yesterday's fail, without any indication it's starting a new process. When I ran it today, that's what it displayed, so at first, I thought I failed again. It had a time stamp at the top from yesterday, mind you, but still, it was confusing and I couldn't clear it. It took a minute or so before I could tell it was running (I thought it wasn't at first) and eventually gave me a Success indication. So all is well, but for other newbies, it's something to be aware of.

Also a new thing I learned - In Projucer, it's when a path is red that we have an error. In David's video, he mentions checking the Modules, but they were all fine, so I wasn't sure what we were looking for that might indicate anything was bad. Now I know it's red paths that I'm looking for.

I'm slowly gettin' it. ;)

Victory! Per Lindon's suggestion, I wiped the drive and installed Mojave, Xcode 10.3 and the newest IPP, then did all the steps, and I now have a Standalone version working.

I'm getting an error with the Plugin version, though. Not a big deal, since the standalone version is all I care about right now, but still, if anyone knows what this is about, the error I'm getting is on this line:
#include "pluginterfaces/vst2.x/aeffect.h"

The error is 'pluginterfaces/vst2.x/aeffect.h' file not found.

I'm thinking VST2 isn't even needed, and in fact, there are some comments above that line that seem to suggest that this is optional. However, I don't see where I would turn that off. My guess is in Projucer, but I don't see a tab for "Don't use VST2."