RStudio Package Manager can be used without internet access, but most organizations will want RStudio Package Manager to have outbound internet access to RStudio's CRAN service. R clients using RStudio Package Manager do not need internet access, just access to RStudio Package Manager.

Can you install R packages without internet?

On Site: Install the Packages

Assuming we've downloaded our packages to a USB stick or similar, on site and without an internet connection we can now install the packages from disk. That's it!

Do I need R for RStudio?

RStudio requires an installation of R 3.0. 1 or higher. You can download the most recent version of R for your environment from CRAN.