You can't bridge regular 802.11 wireless into ethernet at the client side. The on-air addressing requires the client MAC address to be the same as the ethernet packet's sender.

802.11 has the concept of "transmitter address" and "receiver address" in addition to source and destination. Those are MAC addresses too, but they're relevant for the on-air radio management. Things like RTS, CTS, ACKs, and fancier things like beamforming and sounding. The problem is that the design only includes 3 address fields in on-air frames; the AP can specify separate SA and TA (i.e. send a packet for somebody else, SA=real source, TA=AP MAC, RA=DA=client.) There is no mechanism for the client to do the same thing; that would require 4 address fields.

Coincidentally, 4 address fields is exactly what you get with "WDS" / "Wireless Extender" / ... modes. However, these need to be supported, enabled and configured on both the AP and client. The author of the post seems to have no access to the AP to do so (and the AP possibly doesn't support it anyway.)