MarketPress Lite & MarketPress Upgrade

I am trying to upgrade to the new Marketpress and I downloaded the plugin from WPMUDev and I uploaded it using the wordpress .zip file uploader on WP.

I am getting this fatal error when I go to activate the plug in

Plugin could not be activated because it triggered a fatal error.

Fatal error: Cannot redeclare class MarketPress_Shopping_Cart in /nfs/c07/h02/mnt/111116/domains/momatlast.com/html/wp-content/plugins/marketpress/marketpress.php on line 7065

I need to get this fixed ASAP. Is it because I have MarketPress Lite still active? I have done this before and had no problem, but it seems I am having a problem with this upload this time. Thank you