Just a simple setup script that should hopefully work for you!
# Install R
sudo apt-get update
sudo apt-get install gdebi-core
export R_VERSION=4.0.2
curl -O https://cdn.rstudio.com/r/debian-10/pkgs/r-${R_VERSION}_1_amd64.deb
sudo gdebi r-${R_VERSION}_1_amd64.deb
sudo ln -s /opt/R/${R_VERSION}/bin/R /usr/local/bin/R
sudo ln -s /opt/R/${R_VERSION}/bin/Rscript /usr/local/bin/Rscript
# Install Rstudio
sudo apt install libclang-dev libnss3
curl -O https://download1.rstudio.org/desktop/bionic/amd64/rstudio-1.3.959-amd64.deb
sudo dpkg -i rstudio-1.3.959-amd64.deb