I feel the need to clarify this statement:
You do not need the binaries. Those are for the hard-core addicts.
This is not really true, in fact the exact opposite is likely more true. The binaries are pre-compiled versions of R packages. These binaries make it much easier to install packages for novice users. Without these, users would have to compile the source code to install/build the packages. If @ishanigam, has limited coding background what I just wrote might seem like non-sense, the bottom line is that the CRAN team has done some extra work behind the scenes to make these packages easier to install, and the binaries are the result of this work.
@ishanigam You have installed the package correctly. The messages you are seeing are a sign that things have gone well. Now that you have installed the package you want, you can load the package in R by running the code: library(poliscidata). If all goes well nothing will happen (sorta strange, right?). But this just means the package is loaded and ready to use.
Lastly, the message below just tells you where R downloaded the package on your computer before installing it. This is a temporary folder that R uses when installing packages. It gets deleted when the R session is closed. Nothing to worry about.
The downloaded binary packages are in
/var/folders/d7/60f0nfg95d5d8rrksgkngjcr0000gn/T//RtmpNmGDqC/downloaded_packages