In case you were wondering whether the Civil 3D 2016 Productivity Pack 2 is available and where to install it from here comes the post to help you with that. There are two preferred ways to access installation files - Autodesk Desktop App and Subscription site.
This product enhancement is available for Subscription customers from your subscription site (https://manage.autodesk.com/). You can can select your product version and click on "Updates & Add-ons".
This will populate the list of all available updates for all versions of Civil 3D but only those applicable to Civil 3D 2016 will be enabled. From that list you may scroll down until you see Productivity Pack 2.
Second way is to utilize Autodesk Desktop App. First you need to login to your account and then you will be able to see all available updates. This Desktop App is smart enough to know who you are and what products you have installed on your machine and will display what you have been missing.
If you don't see what you are looking you may need to check if you already have it installed or is your login OK.