i downloaded the free trial of Parallels 15 to try to set up a VM with El Cap for a couple of applications that won't work on anything after that OS version that I need for work stuff. i got Parallels installed (machine is running Mojave), downloaded El Cap from my purchases, created the blank VM and it saw the installer and made the image it said it needed. it boots up into the whole Mac Recovery looking screen and lets me select to install the OS. then after about 10 minutes it craps out saying If I let it reboot it just tries again and the same result. I've deleted the attempted VM, deleted the installer app and redownloaded it. I even tried to clone an old VM from when I used Parallels 12 and it opened fine but wouldn't install any updated OS versions. all the instructions online say it should just work but it's not.