Run the suggested command that is shown at https://rustup.rs. Run this command in a Terminal. The script suggests some defaults and asks you to confirm them. This is roughly what it should look like after completing the whole script:

Note that this script attempts to set up rustup for your user by editing your .profile and .bash_profile files. If you are using a custom setup, such as another shell, you may need to add the source $HOME/.cargo/env command manually.

After finishing this script, you can verify that it worked by logging off and on from your Terminal and verifying that the tools are in your path: