I have created a workspace to push files into Sharepoint.
I've created a web connection via FME Options into Sharepoint. I've signed in and tested this connection.
When I bring in the SharepointOnlineConnector transformer, I can find the Authentication account. It's when I got to the "..."s to the right of Site and click on that that I get this warning.

I am connected to the internet. I don't think I have firewall issues.
I am signed into Sharepoint in my web browser too to this specific account. I do work with multiple Sharepoint/Microsoft accounts though on this laptop if that makes a difference?
I was unable to get Sharepoint to work in the workspace, however I have a colleague who can write into this Sharepoint account using my Sharepoint login/password (he writes through FME Server) and write into Sharepoint successfully. As a result he exported a .xml for me and told me to import it.
I have tried that, but am still getting this warning. I notice in the last three lines of the .xml it refers back to his ownername. Do I need to change this?
I wrote the workspace in FME 2022.1, but have since updated to 2022.2.1 which is the same version as my colleague who can write into Sharepoint.

Are there any other troubleshooting or steps I can take before asking IT or give him some really easy to follow instructions? The IT guy works remotely and is hesitant to let any systems he is unfamiliar with into the system, so I'd like to try and figure this out myself if possible.