error installing with R 3.5 / Rstudio version Version 1.1.456

[elenapapaleo]

I tried to install the package with my Rstudio (v 1.1.456) and R v3.5 on a Mac.
using:

install.packages("devtools")
library(devtools)
install_github("vqv/ggbiplot")

but it returns the following error:

"Error: (converted from warning) Setting LC_CTYPE failed, using "C"
Execution halted
Error in i.p(...) :
(converted from warning) installation of package '/var/folders/f1/7bhhfp9s5cggkbvgb0tjhwsw0000gn/T//RtmphcjUdD/file93a4170d51ef/ggbiplot_0.55.tar.gz' had non-zero exit status"

Any comments or suggestions are very much welcome