Hi, thanks for reaching out. The remote file storage (vospace) must be accessed using the storeClient (sc). You already used it to create a directory in your vospace (sc.mkdir('directory')). To write files to your vospace please use sc.put(fr='path/to/myfile',to='vos://directory/myfile'). To read a file from your vospace, use sc.get(fr,to).
The directory 'vospace/' that you see inside your notebook space is just a read-only mounted symlink for convenience. Again, to write to or read from a directory in your vospace, you need to use sc.put() and sc.get().
If you're writing or accessing from the command line of your own machine (using the datalab cmd line client), the syntax is very similar:
datalab put fr=path/to/myfile to=vos://directory/myfile
Hope this is helpful. Please let us know if we can assist further.