Hi there. $9 sounds very cheap for a proper Apple card, but then I am not used to US prices. I don't know any differences between the AX variant - a
very quick search and the AX version doesn't seem well talked about. If there was a readily available card that worked for $9 then I suspect more people would be talking about it?
A further thread indicates the AX is an m2 card?
Does your wifi work? Have you connected USB internally? Do you have another USB device you could connect internally to check that the header is working?
I do not recall having to do anything special to get mine to work; apart from connecting to the internal USB header. I don't think there were BIOS changes, and I can't recall exactly what was needed in Clover re USB patching but if you have used a guide here it will be the same as mine. I just plugged it in, connected USB header up internally, connected antennaes and powered the machine back on and wifi and bt work just like on a genuine mac.