You can’t use vvols for your journal volumes. Here is the link to the Installation & Deployment guide which has our best practices for setup. https://dell.to/2NpAjbm
Please let us know if you have any other questions.
It's fully supported for journals, repository and it should also be noted that we fully support protecting VMs leveraging vVols.
Here's a demo I recently recorded showcasing RPVM protecting VMs using vVols from PowerStore: