The Trendnet TEW-649UB is not able to get an IP address after many attempts with different wifi networks. On bootup the rsu firmware loads as expected and the rsu0 interface is created on my Lenovo IdeaPad Yoga 13 laptop. It even joins the wifi network but dhclient cannot get an IP.
This appears to be broken in OpenBSD rsu(4) as well. In OpenBSD I was getting errors such as the wifi adapter could not send join command and could not send survey command.