Web Services API is enabled for qualified accounts. Caspio Plug-in for Microsoft Office requires the Web Services API to run and as a result is also limited to accounts with API. Package details can be reviewed on the Caspio Pricing page. In your Caspio menu, Account  for  Account Permissions, if Web Services Profiles is not an option, your plan may not include the add-on feature, Web Services API & Plugin for Microsoft Office.  For more information you may contact your Account Manager, or select Change Plan from the Account menu to add the feature.

You can download the plug-in and read the documentation for implementing Web Services.