It should be a piece of cake. You want the bthome hub to act as an access point rather than a router.
On the bthome hub:
1. Reset it to factory defaults (so you don't have any previous settings to worry about).
2. Go into the configuration pages:
a) Switch off DHCP.
b) Assign it a different IP address to the one used by the netgear router (But use the same first three octets). So if your netgear address is 192.168.0.1 then make the bthome hub 192.168.0.2 or something similar.
On the netgear router (IMPORTANT):
Make sure whatever address you gave the bthome hub is not in the DHCP range of the netgear router.
Finally, connect the two routers with a normal straight wired RJ45 network cable. Connect normal network port to normal network port (the same port you would plug a PC into), don't use the WLAN port.