Your phpMyAdmin has been configured with an administrative user ('controluser') to access some advanced features of phpMyAdmin. However, it does not appear that user exists in MySQL. This suggests that XAMPP has
had some glitch in installation, as I believe the XAMPP package normally configures this all for you.
The solution is rather easy; edit your config.inc.php and comment out a few lines by adding // to the beginning of each line. You should do that for the configuration directives for 'controluser', 'controlpass', and 'pmadb', then re-try.
Once you're connected, you can either decide to add the controluser manually or just leave things how they are and not have access to the more advanced features such as bookmarking queries, favorite tables, and so on.