The rule states that all communications relating to your crowdfunding investment must be in writing and conducted through the Republic platform.
After you invest in the company, the founders can message you via a private message, but these communications can not contain any material information about the company that's not already disclosed on the public campaign page.
All communications containing or requesting new material information about the company or its business must be publicly visible to all prospective investors.
On Republic, public communications can happen on the Discussion section and/or Updates section of each campaign.