Attempting to connect Greenshot to Jira

I am using Greenshot for the first time and would like to use the facility to export to Jira.

I have tried configuring the plugin with "https://xxxxxxx.costain.com" which is the URL I would normally used to access our Jira and Greenshot gives me 'Unable to log in' and suggests my username and password are invalid. There are instructions as to how to configure the Jira URL in Greenshot preferences using the old Soap calls to Jira, but I can't find anything that gives me any information on what URL to use with the Jira REST APIs.

I'd appreciate some help with this.

Kind regards

Su