Hi ,
Even if you have configured repeater on 5GHz, you still will be able to connect clients to it .
If you have configured Repeater WAN in bridge mode , you will get IP from Base AP . Better to disable DHCP on Repeater .
If you have Repeater WAN in NAT mode , you will need to keep running DHCP on repeater , but change default IP pool on Repeater from 192.168.11.0/24 to something else .
Below are few article to help you with configuration .
http://community.cambiumnetworks.com/t5/cnPilot-R-Series-Home-Small/Wi-Fi-Range-Extender-between-cnPilot-R-and-E-Series-Access-Point/m-p/73717#M30 --> You can use Both Base AP and repeater as R-series. This one coveres both bridge mode and NAT mode . Just Ignore E-series configuration .
Regards,
Nilesh