Zyxel AG 225H & Mac Networking Challenge PLEASE HELP

Hello, trying to help a friend join network already established at her house. Office is about 200 yards from Linksys router, Zyxel AG 225H "reads" network from office location, so far so good. Following instructions, downloaded Mac drivers fm Zyxel site, loaded Zyxel unit into USB port but have been unable to proceed beyond the Zyxel scanning for networks to join (which it seems to do endlessly). AG 225H is supposed to act as adaptor enabling iMac to join wireless network. But it's not clear what the next steps are. Instructions with Zyxel are poor, their tech support not available again until Monday..

anyone have experience and can please help with suggestions? It's not clear if I need to do active configurations on the iMac in order to activate network.

My friend only has 9Gb (!!) of free hard drive space on iMac which I think could not be helping?

thank you

iMac Mac OS X (10.3.9) Zyxel AG225H, 768 Mb SDRAM, 800 Mhz PowerPC G4, 60 Gb Hard Drive