The releases are available at: https://github.com/Terradue/rOpenSearch/releases
Releases can be installed using devtools
Start an R session and run:
install_url("https://github.com/Terradue/rOpenSearch/releases/download/v0.1-SNAPSHOT/rOpenSearch_0.1.0.tar.gz")
library(rOpenSearch)
Note the example above install the v0.1-SNAPSHOT release, adapt it to the current release