I have a similar problem with devtools::load_all() vs devtools::install
works:
devtools::load_all(path = "~/code/r_mp3_files")
but this fails:
devtools::install(pkg = "~/code/r_mp3_files")
#> Error: HTTP error 401.
#> Bad credentials
#>
#> Rate limit remaining: 55/60
#> Rate limit reset at: 2020-02-09 06:43:22 UTC
#>
#>