Please follow the steps below to manually add the security permissions required.

1. Go to your applications folder 
2. Control Click on the Folder for Mavis Beacon Keyboarding Kidz 
3. Click on Get info 
4. Click on the yellow Pad lock in the bottom right hand corner. 
5. Enter the administrators password. 
6. In the section for Security and permissions set the dropdown next to everyone to Read and Write. 

This should resolve your issue.  If it does not please submit a technical support ticket.