RE200 v2 internet connection

I installed OpenWrt on my RE200 v2 and followed the quick start guide and the relay config guide.

Now I am stuck with needing relayd to continue the latter guide.

My RE200 has no internet connectivity. I am connected to the OpenWRT's web UI via an ethernet cable to my macBook. The macBook has a wifi connection on a different network (192.168.2.x). How do I tell OpenWRT to use the router on that network ( to connect to the internet (through my macBook) so I can update the software package list and install relayd?