you are following a very old tutorial that does not match the version of QIIME 2 that you are running.
On the left-hand side of the documentation page there is a button with a drop-down menu of different release versions:
use this button to choose the version of QIIME 2 that you are running:
or better yet always run the latest version of QIIME 2 and you will always match the latest documentation
The other option is to modify the URL to match the version you are running. SO:
Try this instead: https://docs.qiime2.org/2019.1/
Just a note of interest: the tutorials/documentation will always work because they are automatically run and tested as a part of every single release… this keeps us from accidentally releasing broken documentation! (some details of the text may get stale if we fail to catch it, but the code will always run fine since it is automatically tested)