FFanalytics download error

I am unable to download ffanalytics from github.

The first one ran successfully:
install.packages(c("devtools","rstudioapi"), dependencies=TRUE, repos=c("http://rstudio.org/_packages", "http://cran.rstudio.com"))

An error occurred while running second one:

devtools::install_github(repo = "FantasyFootballAnalytics/ffanalytics", build_vignettes = TRUE,checkBuilt=TRUE)

Following error is shown:
Error: .onLoad failed in loadNamespace() for 'pkgload', details:
call: loadNamespace(i, c(lib.loc, .libPaths()), versionCheck = vI[[i]])
error: there is no package called ‘backports’

Please help me.

Have you tried installing the missing dependency?

install.packages("backports")

It's working now.
package named "ellipsis" needs to be installed.
Thanks for support

Done!

But now the error is: please help

WARNING: Rtools is required to build R packages, but the version of Rtools previously installed in C:/rtools40 has been deleted.

Please download and install Rtools custom from http://cran.r-project.org/bin/windows/Rtools/.
Downloading GitHub repo FantasyFootballAnalytics/ffanalytics@master

The error message is self explanatory, you need to install and configure RTools40 in your system. Click on the link and follow instructions there.

Rtools40 was already installed.

However, package named "ellipsis" was not installed.

After installing, library ffanalytics was successfully installed.

Thank you.