What this framework is
Rule 506(b) is the most common private-placement exemption in the Regulation D family. It allows a sponsor to raise an unlimited amount of capital from accredited investors plus up to 35 non-accredited (but "sophisticated") investors, without a registration statement, and without general solicitation or advertising.
The framework is typically used by sponsors whose LP base is pre-existing — family, friends, prior-deal investors, personal network. The no-solicitation limit means the sponsor cannot advertise the deal publicly, post it on social media, or mention the raise on a website accessible to non-investors.