What they probably meant was that the IMEI isn't in their compatibility database yet. It may or may not getb added at some time but until it does you can't order the eSIM as part of the automated process.
You might want to try the Visible subreddit at: https://www.reddit.com/r/Visible/
There are plenty of workarounds available for physical SIMs; it's a more active forum than this and someone might have a way around it for eSIM over there.
