How to Sign in to Sage 300 as a UI Customization Admin Steps: Visit http://servername/sage300/admin, where servername is the server name or IP address of the web server where Sage 300 is installed.In the User ID field, enter the username of the ADMIN user.Select a system database.Click Sign In.On the Import tab, you can specify packages to import and assign Sage 300 databases for which customizations will be available. Sage 300 Request Support