Right click on the white space next to it, then press "Export as XML" Save it to somewhere easily accessible for Blender, name it what you'd like. Finally back in Blender, press File > Import > Import ...
This is a Blender add-on that allows importing and exporting 3MF files. 3D Manufacturing Format files (.3mf) are a file format for triangular meshes intended to serve as exchange format for 3D ...