The second line of the help text states "The available template fields are listed in the 'Insert Template Tag' drop down list".
I think the confusion here stems from the instructions saying you can "manually type template tags into the template". In this instance, that line of the help simply means that the tags we have provided in the "Insert Template Tag" drop down can be manually typed into the template instead of clicking the drop down and selecting the tag each time.
The templates do not allow for creation of new tags.
I hope this has helped answer your question. If you have any further concerns or questions on this topic please let me know.