R is a popular language used in many areas of research, and if installed by an administrator, not all components can be modified by a user. By installing it as a normal user without administrator rights, you retain the ability to change all versions of software and installed libraries, without needing assistance from IT.

This takes around 15 minutes, and does involve a fair number of steps to complete.  This is all documented with screenshots below, and there is also a bitesize video available from Research Computing that walks through the process, available here:

Bitesize video on installing R on Windows

Installation steps

Download files

Download the version of R you want:
https://cran.r-project.org/bin/windows/base/

The latest at the time of writing was https://cran.r-project.org/bin/windows/base/R-4.0.5-win.exe

Download RStudio Zip file:
https://www.rstudio.com/products/rstudio/download/#download

The latest at the time of writing was https://download1.rstudio.org/desktop/windows/RStudio-1.4.1106.zip

Download RTools:
https://cran.r-project.org/bin/windows/Rtools/

The latest at the time of writing was https://cran.r-project.org/bin/windows/Rtools/rtools40-x86_64.exe

Installation

Once you've downloaded these you should have three files:

Install R

Double click R-4.0.5-win, and a series of dialog boxes will appear.  Unless otherwise noted, just select OK/Next:

You do want to change the destination on the next screen.  In the example, we are using a user called "test".  Select a suitable path to install this to, such as the example here, "C:\Users\test\R\R-4.0.5".

Install Rtools

Double click on rtools40-x86_64.exe
On the first screen, tell it where you want to install (C:\Users\test\R\rtools40 here):

Choose to save version information to registry, but not create start menu icons.

Install RStudio

Right click RStudio-1.4.1106 and select Extract All:

   

Then select a suitable directory to extract it to (in this case C:\Users\test\R\Rstudio-1.4.1106):

Configuration

Using the file explorer browse to where you extracted RStudio, and within the bin directory, double click rstudio:

This will open RStudio up, and ask you to tell it which version of R to use.  Select Choose a specific version of R, and browse to your R install 

In our case this is C:\Users\test\R\R-4.0.5

When it asks you which version, choose the 64bit version:

At this point, the installation and configuration is complete, and you should have a working install of R, RStudio, and Rtools..  If you want to create a shortcut to RStudio for future use, you can right click the icon on the taskbar and select Pin to taskbar.