Implemented Community Builder extension on client's website tnssecurities.in. While Login form showing, Register button not showing. Tried to post this problem on their forum but came to know forum membership not free.
You need to use the Community Builder Login module. In this module there are several tabs. In the tab Login Options, you need the setting Register Login Link. When it is set to Hide you will not see a link to register: set it to one of the other 3 values (Text, Icon, or Icon and text).
The forum is free, you need to register first, and some parts of the forum are read only when you do not have a paid subscription.
It didn't work for me either until I realised that on the Configuration page of Community Builder, the first option entitled "Allow User Registration" should be set on "Yes, Independent of CMS 'Allow Registration'". This, unless you are wanting the Content Management System (in my case Joomla) to do all the registration.