Help installing rstan on OSX10.10.5

Hello,

I am teaching a university course that uses rstan. Sadly, all our computer labs are shut due to the ongoing pandemic. So, I find myself having to help a lot of somewhat nervous psychology students get to grips to installing rStan.

One of the students is having problems, which i think are due to her old laptop. Can anybody point me towards an install guide that will work with OSX10.10.5, (and R v3.3.3). ?

Thanks

rstan requires at least R 3.4.x and is much, much easier to get working with R 4.0.x. I know that people sometimes have reasons not to update the OS, but I think they should always be able to update the R installation.