Error installing Stan on Windows 10, R 3.6.3

I would like to install rstan package in R3.6.3 on Windows 10. I have tried so many times. Since I have to use some old packages which only work in R3.6, I cannot switch to R4.0. However, I could install and use rstan in R4.0. I don’t know what happened. The error code is shown below.

C:/Program Files/R/R-3.6.3/library/BH/include/boost/math/tools/fraction.hpp:84:48: error: 'long double' is not a class, struct, or union type
       using value_type = typename T::value_type;
make: *** [C:/PROGRA~1/R/R-36~1.3/etc/i386/Makeconf:215: stan_fit.o] Error 1
ERROR: compilation failed for package 'rstan

Can anyone help me? Thanks.

Maybe this will help?

Thanks, but it does not work.

Ok thanks for the response. Hopefully someone on a Windows machine will drop by to help.