Yes, you need to update certbot. It's not enough to just point to the v02 API endpoint, it actually needs to speak the v02 protocol.
There's more information on upgrading certbot in this thread:
However, it may be tricky to install on an out-of-support system like RHEL 6. Really, having certificates is the least of your worries, as your system is old enough that it's no longer getting security updates.