Google Apps Users

Google Apps Users

I am the admin for my families Google Apps domain.  My wife needs to use Zoho Invoice so I installed it from Marketplace.  However my user id is automatically added to the Zoho Invoice Users... we only want to use the FREE edition of Zoho Invoice.

How can I as the Google Apps Administrator install Zoho Invoice but have a different user as the Zoho Invoice user under the free plan?

Thanks
Sean