Permissions required for PlasticSCM

I tried adding PlasticSCM as the Source Control, created a new read-only user per instructions but I get this error: "Repo is not accessible. Please check your URL and repo settings."

When I use my admin account for Plastic it seems to work fine. I haven't tried any builds using that account but I get access and can see all my repos.

Here are the permissions for the read-only group I created:

 

Might be worth checking here (https://forum.unity.com/threads/plastic-scm-support-now-available.930651/#post-6214970) as that post discusses something similar and there are Unity staff replying to queries.