Installing r-lib/devtools without admin privledges

I'm facing a different problem while installing the devtools package. I am doing it on a work computer and don't have administrative privilege. Following is the error message:

devtools::install_github("r-lib/devtools")
Downloading GitHub repo r-lib/devtools@master
from URL https://api.github.com/repos/r-lib/devtools/zipball/master
Installing devtools
Downloading GitHub repo r-lib/rcmdcheck@master
from URL https://api.github.com/repos/r-lib/rcmdcheck/zipball/master
Installing rcmdcheck
"//mt6dc1/userdata$/arnabb/MYDOCU~1/R/R-35~1.1/bin/x64/R" --no-site-file --no-environ --no-save --no-restore  \
  --quiet CMD INSTALL  \
  "C:/Users/arnabb/AppData/Local/Temp/7/Rtmp4cONIv/devtools275c32622db2/r-lib-rcmdcheck-73f5b8a"  \
  --library="\\mt6dc1/userdata$/arnabb/My Documents/R/R-3.5.1/library" --install-tests 

'\\mt6dc1\userdata$\arnabb\MYDOCU~1\R\R-35~1.1' is not recognized as an internal or external command,
operable program or batch file.
In R CMD INSTALL
Installation failed: Command failed (1)
"//mt6dc1/userdata$/arnabb/MYDOCU~1/R/R-35~1.1/bin/x64/R" --no-site-file --no-environ --no-save --no-restore  \
  --quiet CMD INSTALL  \
  "C:/Users/arnabb/AppData/Local/Temp/7/Rtmp4cONIv/devtools275c10cb579a/r-lib-devtools-5e762cd"  \
  --library="\\mt6dc1/userdata$/arnabb/My Documents/R/R-3.5.1/library" --install-tests 

'\\mt6dc1\userdata$\arnabb\MYDOCU~1\R\R-35~1.1' is not recognized as an internal or external command,
operable program or batch file.
In R CMD INSTALL
Installation failed: Command failed (1)

Can you kindly help me out!

Thanks in advance!

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