I have read the main post on this several times, it means nothing to me I'm afraid. The GUI mapping isn't quite right (z trigger missing for example) and although there is a certain amount auto config'd there are buttons missing and it's not exact. The link below is the one i assume will get things working correctly, but as I say, afraid I cannot fathom where to begin - if someone could provide a very basic guide/link to one that would be great. Thanks in advance.
Running 6.1.1 on odroid xu4.
https://github.com/recalbox/recalbox-os/wiki/Configure-N64-controllers-(EN)