Download and install this LeapFrog utility program

Run the utility and select the option "Uninstall LeapFrog Connect", then "Complete..like it was never there." 

 

When the uninstall is complete, restart your computer.

 

Next, run the permissions repair function in Disk Utility, then sign in as an administrator and try the install again: 

1.To open Disk Utility, from the Applications folder, open Utilities, and then double-click the Disk Utility icon. 
2. In the column on the left, click your startup disk. 
3. Click the First Aid tab, and then click Repair Disk Permissions. Disk Utility will reset any files and folders with incorrect settings.