To install the package, use the following code.

install.packages("devtools")  
install.packages("learnr")  
devtools::install_github("chrisaberson/MVstats")  

To run a tutorial, use this code..

library(learnr)  
library(MVstats)
run_tutorial("Logistic", package = "MVstats")  #For logistic
run_tutorial("Mediation", package = "MVstats")  #For mediation

After you run this code, the tutorial will open, either in a separate RStudio standalone window or in a tab on your browser.

If this doesn’t work, you likely need to update your rtools. Go to https://cran.r-project.org/bin/windows/Rtools/ and download the most recent version (for your platform (Note: Rtools is just for Windows, I am looking into other platforms).