Loading external geometry from Dropbox is not going to work due to the CORS policy, I’m afraid. Dropbox, as many other online storage providers, doesn’t provide the flexibility to define MIME types and CORS configurations so we recommend using a service such as Amazon S3 to store your external geometry.
Alternatively, you can use the SDGeomteryInput component to import OBJ or DXF models from Dropbox. Importing TXT, CSV, JSON, JPG or PNG file formats works as well because of our backend implementation which passes them through to the client, hence CORS is not an issue. More in this documentation article: