hope this link is useful

https://cran.r-project.org/bin/windows/base/rw-FAQ.html

regards

Interesting

The Arlequin 3.5 website state this :

New R functions for R package ver 3.01. The zip file contains a directory called Rfunctions, which needs to replace the Rfunctions directory located in your Arlequin home directory.

Maybe get in contact with the Arlequin team to assist you.

Never worked with Arlequin but you might find this discussion usefull:

https://www.biostars.org/p/263865/

I've figured how to do this. If anybody comes across this thread and requires some help please do ask.

Best