Why can't I install Forecast plug-in?

[Emma Sinclair]

I get the message:

An error occurred while provisioning the user for this add-on. Please try installing it again, and if then problem persists then contact Atlassian support.

[Ting]

If you're the Site admin, can you check if the default application access is set up?

1. Go to Site administrations > Application access
2. Click on View Configuration button on the top right corner  (you can use direct access: <instance-url>/admin/accessconfig
3. Make sure there's at least a default group for JIRA