A ZIP file is a container to put other files in and compress them - what’s inside the ZIP file is what’s important. If you have a ZIP file, you should extract the contents first, because there are so many variations in what could be inside the ZIP file.
CoSpaces Edu doesn’t currently support glTF or glb files, but you can convert these in Blender to OBJ+MTL files.
Hope that helps! Let me know if you have any further questions about this.
Geoff @ TechLeap