The system tried to use your current email address (the one used to login in the portal) with a username in the forum that also has that email address as main or alternate.
The association has failed because engineering@ringcentral.com is not bora_bora... (your forum user email address)
The system cannot attach the forum group “Enterprise User” to your forum user automatically
In your case, things work anyway because I assigned you the Enterprise User group in the forum manually.