If you ever have an issue with Revit being unable to upload a model for a cloud rendering, you will likely end up on this Autodesk Knowledge Network article, and may eventually get to the suggestion to disable the addins to see if there is a conflict with one of them, which links through to a second Autodesk Knowledge Network article.
The second article helpfully lists a number of addins that should be left in place if you are using the Collaboration for Revit service. What it does not list is the addin that generates the Render in Cloud tool on the View ribbon tab, on the Presentation panel. It is rather hard to test whether removing the addins allows a cloud render to go through if the tool to initiate a cloud render is gone.
I was able to work out that the RaaSForRevit folder should not be removed from the W:\ProgramFiles\Autodesk\Revit 2018\AddIns folder if you want to have the Render in Cloud tool.