Yes, one of the two TELUS Boost WiFi needs to be hard wired into the T3200m modem/router.
The reason is due to difference in technology. The T3200m does not have the ability to create a mesh network for the Boost WiFi extenders to work.
It sounds like you have the Starter Pack (includes 2 Boost WiFi's). This is great for coverage up to 2000 square ft. If you need more coverage, you can purchase an expansion pack (includes 1 Boost WiFi) to cover an additional 1000 square ft.