Hi, and welcome!
Please see the FAQ: What's a reproducible example (`reprex`) and how do I do one? For future reference using a reprex, complete with representative data will attract quicker and more answers.
Here, we need some clarification.
readRDS is akin to unzipping a file; it's not used to install libraries or run code. Its general purpose is to save an object after it has been constructed, so it doesn't have to be re-run every time.
In the Console pane, does the code
2 + 6
#> [1] 8
Created on 2020-03-12 by the reprex package (v0.3.0)
work?
If so, the way to install packages is
install.packages("dplyr")