To Export a lookup to either XLS or CSV firstly create your lookup of records for example you may run a Query for records of a specific type or within the "Wizard"
Go to the Reports Icon in the left hand toolbar and select the Contacts Wizard
Now go to the Contact Wizard
From the drop down select the one that says Export
If you do not see this you may either be denied reports or denied the reports wizard that allows exporting or you may be on an older version.
At the bottom of the page you will see the area where you limit the report to only pull your specific lookup and where you simply change the report extension to XLS or CSV
Now press "Request Report"
Once ready your report will either show on screen or will be in the Main Library in the “My Reports” folder this depends on your browser settings.
Support is available if needed please submit a ticket to firstname.lastname@example.org
If you have produced a CSV file and you want to convert it to xls then you may find this video from Youtube to be of value
Reports are accessed via reports.html. there is for comprehensive KB article on Reports and Export restrictions here
A user guide is located at https://wiredcontact.co.uk/Manual/