I've never used SteadFast's CDP backup solution before so I'm not sure how you acquire the Linux Agent. I purchased my license directly from R1Soft and downloaded the agent from their website. The installation is about as easy as it gets.
I suspect the plan you have will be even easier as they'll have the CDP server setup for you. Is there a reason you haven't contacted their support team? Surely they'll assist you.
We can certainly assist installation on any server located within our datacenter. For servers outside our datacenter we can provide support for any error messages one may see but cannot log directly into the machine for liability reasons.
When you signed up for service you should have received an email with your login details as well as links to documentation as well as links to downloading the agent software.
Please do feel free to email our support department at [email protected] for assistance.