Once you purchased the software you should have received an email confirmation with the link to the downloads. Depending where you are located you can try: my.esri.com or accounts.esri.com
Once you have signed in, using your ESRI credentials, there should be various tabs for download and licensing. Mine are under the "My Organizations" tab but I have an enterprise license.
Start with the Desktop 10.x version installation and add the other needed components. The Desktop install covers the majority of the needed components.