unable to download the all in 1 package

[nase...@gmail.com]

hi. when i am trying to download the all in 1 package , i click on download installer and it takes me to another website with title "

Hard-to-Reach Population Methods Research Group".  i tried downloading R first and then continue by typing "install.packages(c("JGR","Deducer","DeducerExtras"))

library(JGR) JGR(), but i am getting error message "  package ‘rJava’ could not be loaded" i cannot continue my online course without getting this fixed. any suggestions? thank you