Using Firefox 57.0.4 (x64); attempting to download a ticket from a atlassian hosted jira instance.
You can't, because FF complains about the HSTS configuration
Your connection is not secure
The owner of api.media.atlassian.com has configured their web site improperly. To protect your information from being stolen, Firefox has not connected to this web site.
This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox only connect to it securely. As a result, it is not possible to add an exception for this certificate.