You can download the latest R Studio 0.99.491 and install for FREE in this link. However if you need support then you need to agree to a monthly term to support you and your production system, and you can compare it from this link about the pricing for your desktop and server.
I have downloaded the RStdio-0.99.491 and have started installing and provided you the below screenshots for your reference.
In here, you have option to choose your folder and it also gives you the amount of space required for this installation. I know, I am running out of space, but I am doing this in my virtual machine.
Here you get option to add to the start menu and create shortcuts. I chose the default options in below screenshot.
As you can see below, the extraction and installation takes place for about couple of minutes.
That’s it. We are now done with the installation of R Studio.