First be logged as a JIRA administrator and then click on the visible only to such user cog icon to access "Projects":
In order to export projects to Excel perform "export to Excel" action:
Evaluation license only warning:
You have evaluation license - it allows to export only 5 users. Please purchase full license to be able to take full advantage of the Admin Tools for JIRA.
The export form wizard open. Select a field you want to export. Order of the fields can be changed by drag and drop technique.
Press"Save File" button to download Excel file at a desired location.