Some hostings servers like GoDaddy or related present some issues caused by security restrictions of that ISP/Hosting solutions. We recommend you to backup all your entire old Joomla! site and copy it in your local Apache/IIS enviroment.
The first step to use jUpgradePro is to install a new Joomla! v3.8. To do this you should download Joomla!. Would be helpful to visit this site http://www.joomla.org/download.html
This explanation about how to install Joomla! is better than i can explain, so i recommend to follow the Joomla! community documentation.
jUpgradePro is a Joomla! extension so has the same requirements. https://downloads.joomla.org/technical-requirements
To download the extension visit: https://matware.com.ar/subscriptions/jupgradepro-subscription.html
jUpgradePro v 3.8 is a Joomla! 3.8 component, and as such is installed using the Extension Manager (Extensions > Install/Uninstall).
From the main Joomla! administrator page, click on Help >> System Info. Click on the "Directory Permissions" tab and make sure all the folders are "Writable". If your temp and log folders in joomla are not writable make sure the path specified for respective directories are correct (they are supposed to be in root directory), in configuration.php file.