Rstan 2.26 and cmdstanr .zip files?

I am having a no luck installing the latest development version of rstan using this:
install.packages("rstan", repos = c("", getOption("repos")))
on my work computer. It works fine on my own laptop. I have also tried using the remotes package and downloading Stan 2.27 with install_git() as described here
It would also like to install cmdstanr.
I am pretty sure this has something to do with the clamped down security on my work computers, given that everything works fine on my laptop with the same version of Windows 10. The only way I can install any R package on these work computers is by using options(download.file.method="libcurl") and a repository that is http.

Question: Is there some way to download .zip files for the latest development rstan and for cmdstanr, save them to my machine, and then install them in R from a local file? (sort of like one can do for packages on CRAN) I’m sure this is possible, but I couldn’t find where to do that on the Stan website or GitHub.
I’m sure that is a dumb, easy to answer question, but I’m hoping someone could direct me to the right place!

I downloaded the file from GitHub and then used the solution to the question here r - How to install a package from a download zip file - Stack Overflow to try to unzip and build it using this code:

file.rename("rstan-develop", "rstan")

Sys.setenv(PATH=paste(R.home("bin"), Sys.getenv("PATH"), sep=";"))

shell("R CMD build rstan")

install.packages(list.files(pattern="rstan*.tar.gz"), repos = NULL)

But I get the following error:

* checking for file 'rstan/DESCRIPTION' ... NO
Warning message:
In shell("R CMD build rstan") :
  'R CMD build rstan' execution failed with error code 1

I am unfortunately out of my league when it comes to installing packages like this. If anyone knows how to download and install the latest rstan and cmdstanr from GitHub and install from local files on the machine, it would be most appreciated!

So I pulled out the folders in the .zip files called StanHeaders and rstan (inside another rstan folder) and tried remotes::install_local("C:/Users/MyUserName/Desktop/StanHeaders") which seemed to actually try to get somewhere before throwing this error:

using C compiler: 'gcc.exe (GCC) 12.2.0'
make: *** No rule to make target 'nvector/serial/nvector_serial.o', needed by 'StanHeaders.dll'.  Stop.
ERROR: compilation failed for package 'StanHeaders'

@andrjohns or anyone else? Thanks!