I selected the aml-s9xx-box image. Thanks to SteeMan for the instructions. I haven't created u-boot.ext. Armbian has booted up. I will continue testing.
Downloaded the official version Armbian Imager. Created a bootable USB drive. Edited the file extlinux.conf for the TV box. I tried to install it, but nothing happens (I pressed the button inside the mini-jack; the USB indicator flashes five times, and Android boots up). REGLinux boots up and installs, I can play games on it. What am I doing wrong?