The extension operates with Salesforce Web-to-Lead. You will need to create a Web-to-Lead form in Salesforce. Once you have done that, you can use the OID from the Web-to-Lead form to map your WP-Members fields to Salesforce fields. You won’t actually use the web form that Salesforce creates, but instead will send information from the WP-Members registration form to be processed as a Salesforce Web-to-Lead entry.
NOTE: This is for the Salesforce Integration extension, extension support, and one year of updates. If you need WP-Members core support, choose one of the support options here.