"Matureland galleries" does not appear to be a recognized institution or a specific established art movement in the standard contemporary art world. It is likely a niche online platform, a misspelling of a specific artist's project, or a reference to a specialized community. Sothebys Institute of Art
Because there is no primary official source for a "Matureland Gallery," a "proper paper" on the topic would instead focus on the broader structural categories these types of galleries fall into, such as niche online galleries community-driven artist initiatives 1. Classification of Contemporary Galleries