When working with your own package, you can use devtools::install_local() to install either from a local directory containing source package, or either from a build source packages tar.gz. See the help
You can also install a package you build locally with install.packages("<path-to-your-package>", type = 'source', repos =NULL). see help(install.packages)
You tried it but not providing the good path to your package in pkgs argument.
Can you try to install correctly as explained in docs and see if it is ok ?