Hi Paul
I have been corresponding with mcb047 about a similar matter, which is knowing how to unzip the X-Plane Installer.zip file and then knowing what to do after that?
The only difference between you and mcb047 is that you are downloading a digital copy of X-Plane 11 whereas mcb047 is installing from a DVD set.
However following a bit of research, I believe that you must be referring to the X-Plane 11 Installer.zip file that you've downloaded from LR's website as a prelude to downloading the full X-Plane 11 application, is this correct?
If I have assumed correctly then, I have prepared a number of instructional slides that may be of assistance, per the following link :- http://questions.x-plane.com/?qa=blob&qa_blobid=5329009325588394983
Also please refer to this link, which is Laminar Research's instructions on how to install the Digital download:- https://www.x-plane.com/kb/digital-download-install/
I think the main issue that your having though, is how to download and unzip the X-Plane Installer.zip file, which is where my slides may help?
If you need any further information, please just let me know?
Regards