I need to install a few Bioconductor packages and dependencies into an R system that exists on a server that does not give users internet access. It seems the only way anybody can get files onto the server from the "outside" is to use ftp. My R system is 4.0. To get my R packages installed on the server, I use miniCRAN to build a local repository, ftp the local repository onto the server, and then install the R packages locally. The help material for miniCRAN talks about using biocLite.R for Bioconductor but that approach seems to be outdated by Bioconductor's BiocManager. The information given in the miniCRAN material only works for older versions of R. How can I get Bioconductor packages and dependent packages into something like a local repository, which I can then ftp onto my server, so I can install from a local "Bioconductor" repository?

I think you're looking for the site_repository= argument to BiocManager::install(). See also the 'offline use' section of the BiocManager vignette.