Problem definition:

As per the design, we do not notify customers about other requests raised within a project due to security reasons. If customers wish to share the request with other users or notify them about their request then they can choose to share their request with the customer or one of the organization

Suggested solution:

Provide the option to notify customers without a license about all newly created issues in a service desk project

Workaround:
https://confluence.atlassian.com/jirakb/add-request-participants-automatically-when-creating-an-issue-in-jira-server-777026955.html