The Private and Public designations for groups do not impact your ability to share a survey with a customer. If you have your group set as ‘Public’, it means that a user of another group on SurveyBot can share a survey with your group without being a user of your group.
For example: Your company is ABC, and company XYZ performs a survey with a customer. Company XYZ wants to share that survey with your company but does not want to add you as a user to their XYZ group. If your group (ABC) is set as ‘public’, it will appear in the list of possible group collaborators, allowing a member of XYZ to add your group to that individual survey, giving you and the rest of the members of the ABC group access to that one survey.