The standard armbian documentation only applies to the standard armbian builds.  The builds by @balbes150 are a fork of the standard armbian code for Android TV boxes (instead of standard SBC boards) and therefore you can't use the standard documentation as there are a number of differences.  To install into emmc look in your /root directory and you will see a set of install scripts.  Choose the one appropriate for your CPU and run it for installation into emmc.  The current active thread of dis