gorzka You don't really need to install rar, you can download the binary from https://www.rarlab.com/download.htm, it's a gzipped tar package, you can place rar and unrar where ever you like; I like to keep rar in ~/.local/bin which is in my path.
I'm not sure I've ever used unrar, I just use rar e or rar x which does the same thing.
