How to go from Lightroom 5.7 to "Lightroom Classic"

So I finally bit the bullet and acquiesced to Adobe’s subscription model and bought a Lightroom “plan” with lightroom classic.   I attempted to open my Lightroom 5.7 .lrcat file by right clicking and opening with the freshly downloaded "Adobe Lightroom" app (I'm assuming this is "Lightroom Classic".  "About Lightroom" says it's "Version 8.2") and got an error stating that it’s not compatible and needs to be updated to a Lightroom 6 catalog, but Lightroom six isn’t available for download. 

I opened the new Lightroom Classic application, and it immediately wanted to try and upload to the “cloud”.   When I switched to looking for local folders it refused to look into subfolders and I don’t see the “include subfolders” tick-box like the one shown here:  https://community.adobe.com/t5/lightroom-classic-discussions/lightroom-classic-import-include-subfolders-search-entire-disk/m-p/11349218  I also see no “Import Photos” menu option.  I'm not sure what "Import Profiles and Presets" is supposed to do.

My hope/goal is to use the new “Lightroom Classic” in exactly the same way I have used the older versions Lightroom.  I only upgraded for compatibility with newer Mac OS versions and Nikon NEF files.   This is on the same computer (2018 Mac Mini) with the Lightroom catalog and images stored on a USB-C connected external HD.  In an ideal world I’d just do what I did when I went from Lightroom 2 to Lightroom 5 and simply imported/upgraded my catalog, which was seamless.  If that’s not possible how exactly can I “import” nearly 30 years of old images into the new Lightroom without having to walk through the Year/Day subfolder structure?  Preferably keeping edits and tags.  Is this possible without using the “Cloud option”.  I’m perfectly fine with and have a strong preference for primarily working locally. 

Thanks