Use Composer to install the Digital River Extension for Magento.
Run the following Composer command in the root of Magento:
composer require digitalriver/module-drpay
Update Magento to execute the install and update scripts in the command line in the root of Magento by executing:
In the Magento Admin panel click System, click Cache Management, and then click Flush Cache Storage.
Log out of Magento and then log back in.