Hi Mathews, a couple of questions:
1. Have you created the PowerClient application in Powerbuilder already? (Created using File - New - Project - PowerClient)
2. Do you have access to the web server and web root directory on Linux?
If you have done both of those things I think you just need to Package the PowerClient as a Zipped file as it shows on the link you provided. Copy the zipped file to the web root directory on Linux and then unzip it. It should create two new directories under the web root, one called CloudAppPublisher which will have the cloud app launcher and PB runtimes and the second directory will be named after the App name from your PowerClient setup.
E.g. If you have an App Name MyApplication you would package the application as a zip file and unzip it to the web root of your Linux server (e.g. /var/www/html). After you unzip it, you should have two new directories on the Linux Server (/var/www/html/CloudAppPublisher and /var/www/html/MyApplication). If your Linux server is called www.myserver.com then you would access the PowerClient application by browsing to www.myserver.com/MyApplication in a web browser. It should show you the Welcome page you've shown above.
Obviously you'll need to substitute your App Name, web root and server name in the above for it to work for you.