This typically means that something interrupted the installation process.
If no categories are populated after installation, please reinstall Magetsync and make sure cache is enabled before installing. The quickest way to re-install is by simply deleting the MagetSync entry under the core_resource table of your Magento store and flushing the cache afterwards.
If this still doesn't fix it. Please make sure you upload all MagetSync files to your server via your preferred method (FTP/sFTP/scp) and delete the MagetSync entry once again.