You simply just open CCC and make all the lights green, it's up to you how much of what is there you need to install. This is why CCC is handy as it keeps track of what you have.
If you also have older versions of Sonar you might want something from those as well. It is said we should always install from the bottom up and this is good advice, just do a bare bones of a few older versions to get the included plug ins and V Vocal which are not part odf SPLAT. I have had no issues with a nice fresh install using CCC and then I also added a few things from my 8.5 and x3 version after the fact. You don't have to even install the old version unless you want V Vocal.
If you dig around there are some threads that list what was included in the older versions.
If what you are asking is should I install all the older versions of Platinum the answer is no, The latest version from October is cumulative.
And don't forget to then back up the CCC download folder to a safe place. As well as log on to your my Products page and copy paste or screen shot all your serial numbers. You may need those in the future if the servers shut down.