How do you configure N64 controller?

I bought a Retro-bit 8Bitdo N64 controller but the auto config maps the controller’s B button as the A button and the controllers A button doesn’t do anything.

If I go to Settings > Input > Input User 1 Binds > User 1 Bind All, I can’t for the life of me figure out what buttons to press.

Similar thread posted @ N64 USB controller not working properly

I am also having this problem and just can’t seem to figure it out. Read that the C-Down was used as the B button and the A button was configured to the B button. However this doesn’t work and menus where you need to press the “B button” to go back none of the buttons do anything. Any information on fixing this would be greatly appreciated.