Install R packages (leaflet and flexdashboard) on an AWS instance

Question

I have recently started using AWS servers to launch R instances.

However, I can't seem to install these following packages : flexdashboard and leaflet.

> install.packages("flexdashboard")
Warning in install.packages :
  unable to access index for repository https://cran.rstudio.com/src/contrib:
  internet routines cannot be loaded
Installing package into ‘/home/rstudio/R/x86_64-pc-linux-gnu-library/3.6’
(as ‘lib’ is unspecified)
Warning in install.packages :
  unable to access index for repository https://cran.rstudio.com/src/contrib:
  internet routines cannot be loaded
Warning in install.packages :
  package ‘flexdashboard’ is not available (for R version 3.6.0)

and

> install.packages("leaflet")
Warning in install.packages :
  unable to access index for repository https://cran.rstudio.com/src/contrib:
  internet routines cannot be loaded
Installing package into ‘/home/rstudio/R/x86_64-pc-linux-gnu-library/3.6’
(as ‘lib’ is unspecified)
Warning in install.packages :
  unable to access index for repository https://cran.rstudio.com/src/contrib:
  internet routines cannot be loaded
Warning in install.packages :
  package ‘leaflet’ is not available (for R version 3.6.0)

Sorry if this is a stupid question. I only have experience using RStudio and am not familiar with Linux environments Thank you for your help