I got the latest version on this forum that's notarized to work with Catalina, downloaded the SheepShaver folder, followed all the directions, got a Mac OS ROM file to use. The setup guide explains the program will just quit if it doesn't have Mac OS ROM in the same directory.

So I've got everything ready, fired up SheepShaver, and... it just quits.
I've tried everything I can to get it working. Found "compatible" ROMs everywhere I can, tried switching out Old World and New World ROMs, put the SheepShaver folder in several different directories in case certain ones have restricted file-writing privileges (Desktop, Applications, even an external hard drive), tried dropping the ROM straight into the Resource fork, ran the "delete prefs" script even though this is the first SheepShaver file I've ever put on this Mac. Nothing. Always the same result.
I even got this program called "SheepShaver Wrapper" which supposedly takes care of all this for me. But when I drop the Mac OS ROM on it, according to its instructions, I get this error:

Here's some other pertinent information, if it's relevant:

I've heard someone say Retina-display MacBooks make SheepShaver go crazy, but these errors seem more in line with some screw-up in the program's default options. I'm able to run SheepShaver perfectly fine on my Windows PC, since SheepShaver GUI still runs fine on it. If I could get into SheepShaver's preferences on Mac, I could tell where to find the ROM file, or fiddle with its display options so that the Retina display doesn't make it crash, but it doesn't stay open long enough for that.
What should I do? Did I screw something up, or is this an unanticipated bug? I'd rather not have to resort to QEMU for my Mac OS 9 fix, if I can help it.