In summary:

1.
Archive and repath your scene to a new folder.

2.
Open your repathed scene from that folder.

3.
Export vrscene from within the V-Ray plugin to the same folder.
‍(ticking the 'stripped paths' checkbox)

4.
Zip that folder and upload the zip file to render.heata.co

We're using V-Ray 5.
Let us know via chat or email if you want to use another version.