Unable to install from github 'susanathey/causalTree'

Question

I want to install the package 'causalTree' available from Susan Athey's github. Whenever I try to install it I get an error message and thus the package is not installed.

I installed Rtools in my computer, from RStudio I installed 'devtools' and tried to install the causalTree package as follows:

install.packages("devtools")
devtools::install_github("susanathey/causalTree")

After which I got the following message:

* installing *source* package 'causalTree' ...
** using staged installation
** libs
C:/rtools40/ucrt64/mingw_64/bin/gcc  -I"C:/PROGRA~1/R/R-43~1.1/include" -DNDEBUG     -I"C:/rtools43/x86_64-w64-mingw32.static.posix/include"     -O2 -Wall  -mfpmath=sse -msse2 -mstackrealign  -c CT.c -o CT.o
/bin/sh: line 1: C:/rtools40/ucrt64/mingw_64/bin/gcc: No such file or directory
make: *** [C:/PROGRA~1/R/R-43~1.1/etc/x64/Makeconf:265: CT.o] Error 127
ERROR: compilation failed for package 'causalTree'
* removing 'C:/Users/Roberto/AppData/Local/R/win-library/4.3/causalTree'

I do not know if this helps but I saw some notes on looking for the "gcc":

Sys.which("gcc")
                                       gcc
"C:\\rtools43\\X86_64~1.POS\\bin\\gcc.exe"

My R version is 4.3.1 "Beagle Scouts"

Does anyone know how to properly install this package?