This category is for questions regarding the installation and use of RStan. If you have installation issues then please provide as much information about your system as possible, especially the output of the commands
writeLines(readLines(file.path(Sys.getenv("HOME"), ".R/Makevars")))
and
devtools::session_info("rstan")
Also, do check out the RStan Vignettes in case your question may already have been answered.