Hello, Emma, thanks for your help.
Yes, I have verified it looging as the user with that role, you can see it in the screenshot attached.
When I try to add it with an admin role, I can add any resources (we have other roles apart form the admin that can add the URl reource too). You may notice that there are other resources that cannot be added with this role.
I have also tried to map the permissions that have anything to do with the URL resource with one of the roles that can add this resource without any success.
I hope you can see anything that I am missing.
Thanks again for your help.