Download the latest danginx from https://portal.syslint.com/downloads.php. You may need to login to this portal before downloading.
The file will be in a gtar format with a name like danginx.X.Y.tar.gz , where X.Y is the version . Now upload this to your server and install it as follows:
# tar -xzf danginx.X.Y
# cd danginx/
# sh install.sh
Now the installation has been completed. If you are upgrading from a lower version below 4.0 , please make sure to upgrade the license to new version before installing it. You can simply open a support ticket from your client are for upgrading your licenses. It is free.