I am not a Cloud user. If that happened on my desktop version, it would mean that I have to install the packages first. The command for that is
install.packages("tidyverse")
There is also a menu Tools -> Install Packages that brings up a dialog where you can type in the package names with no quotes. Tidyverse is fairly large, so the installation will take a few minutes. After the installation, you can run the library() command to load the package.