Hello.
I am new here, in FreeBSD. English isn't my first language, so, please, be patient. I have a TL-WN725N device.
When I use the urtwn firmware in OpenBSD, I only need to do this:
# ifconfig urtwn0 nwid WI-FI-INTERFACE wpakey PASSWORD
# dhclient urtwn0
(It could be "nwkey" instead...