looking for oscam binary to LEDE 17 - OpenWRT based FW on router MIPS (D-Link)

au=1 is enabled to oscam.conf and oscam.user.

Leave out the oscam.conf file, it is not needed for this purpose. Oscam.conf file is used for global settings that apply to the entire Oscam. You must allow the specific user to write EMMs and specify where they can be written, exactly which one reader, as I already mentioned. However, you must enable the AU - but on both sides - both on the softcam-server side and on the softcam-client side, as I already wrote.