First off, only the young guys with good eyes might be able to see that. I sure can't read what it says.
Secondly, why don't you just use a platform that is known to work well for gnuradio (Linux Mint 17.1 64-bit preferred, 32-bit if you must).
And then read the thread below in its entirety and make yourself aware of all of the sage advice and great instructions given by PiccoIntegra and KA1RBI:
http://forums.radioreference.com/so...-virtualbox-project-run-op25-windows-7-a.html
I don't care if it mentions OP25. A prerequisite of installing OP25 is having gnuradio installed and functioning. So that thread covers it all.
I'm sure there are other Linux distros out there that work well, but we already know without a doubt that the procedure PiccoIntegra outlines in that thread works great on Linux Mint 17 -- more than one person [with one of them being me] have had success.
Installing on any other OS / distro may yield you less than stellar results, and if you don't know Linux you shouldn't attempt to install it using the method outlined in your RTL link unless you are prepared to do some legwork and learn something about Linux.
Following Pico's instructions, you also may be installing newer versions of gnuradio/etc than you might end up installing if you follow some other directions.
Mike