The download is a zip with a right and a mirrored left antler, the design file, and print notes. Both STLs are single closed solids, checked for open and non-manifold edges before you get them.
Each antler is one complete part, standing on its flat base and turned on the plate if that's what it takes to fit the P2S. The print notes list Bambu Studio settings for your filament: tree supports, a brim, and the right nozzle for PLA Wood. Sizes are in inches; the slicer settings stay in millimetres, as Bambu Studio uses them.
Save to library keeps designs in this browser, on this device. The STL zip also holds a design file; node tools/build-antlers.js <name>-design.json --res 0.35 builds it at higher resolution offline (a crown fitted to a head scan finds its scan in the same folder).