If you know the URL of your FastClose server, as an Administrator, you can visit this by opening a browser and navigating to http://[myservername]:5101 or https://[companyname].fastclose.uk depending on whether you have deployed FastClose internally or have SaaS/hosting.

Alternatively, within the Designer app, visit the Administration tab in the ribbon and click on FastClose Server:

or click on the URL in the bottom right of the Designer App window:

This will display the web interface:

Login using an account with Administrative privileges.