You may copy, modify, publish, distribute, and sell this icon without an attribution condition. Public-domain treatment varies by jurisdiction, so retaining the Unlicense statement is the clearest approach.
Folder with plus sign for creating new folder or adding files. This line icon belongs to System Uicons, a source set with 432 SVG records. Its recorded source grid is 21px. It is indexed under folder add, new folder, add folder, create, add folder, new folder.
Choose SVG for scalable interface artwork or PNG for a raster image in a presentation or document. Export sizes and access depend on your plan. Resizing, recoloring or converting a file does not remove the source license obligations.