Most free plugins do not cut floor openings automatically. You must use SketchUp’s "Intersect Faces" tool manually.
Leave a comment below with your SketchUp version (e.g., SketchUp 2024 Free vs. Pro), and we will help you find the exact plugin file that works for you. instant stair plugin sketchup free download
Go to View > Toolbars and check the box for "Instant Stair" or "1001Bit." Most free plugins do not cut floor openings automatically