Hi @gretha
Thanks for reaching out to us.
Business Directory uses the default WordPress login and registration pages as we don’t have our own. You will need to use a membership plugin to change these pages.
There are some good membership plugins, that work with BD. For example, MemberPress, s2Member, Simple Members Only etc. Here are some more suggestions: https://www.wpexplorer.com/wordpress-membership-plugins/
You can see how to connect any membership plugin to Business Directory here: https://businessdirectoryplugin.com/knowledge-base/general-tab/#registration-settings
I hope that helps. Please let me know if you have any other questions or issues!
Best,