DocHub currently does not support simultaneous collaboration on a document, so your PDF isn’t going to refresh automatically, and we even recommend to not edit the same document at the exact same time as someone else to avoid any conflicts and the chance of losing an edit due to someone else trying to edit the file at the same time and one of the edits being blocked due to the document being updated to reflect the new edits by the other person. It’s recommended to edit the file one person at a time and to take turns (i.e. not attempt to edit the same document at the exact same time).
We plan to add the ability to collaborate on a document simultaneously with auto-refresh, etc. though I don’t have an ETA on when this will be fully supported in DocHub.