Once you have the koreader folder, from the download package, in the .adds directory of your device, KSM should see it when it is started up. You might want to try the current nightly for KOReader at "
http://build.koreader.rocks/download...ec_2018-03-25/", as there have been a number of Aura One related fixes since the "stable" release. There are also versions for Kindle, you could try.
Luck;
Ken