Part of your problem is that the tutorial is ahead of the release. NP 1.3.0 is not out yet (though you can get it at GitHub on the Download page:
https://github.com/BobRay/newspublisher/downloads).
It should be out soon.
In the meantime, you can
Duplicate the Administrator policy template
Edit the duplicate by right-clicking on it and selecting "Update Policy Template"
Add the allow_modx_tags permission to it by clicking on the "Add Permission to Template" button
Save it.
Create a new Policy based on the duplicate Admin template you just created.
Use that policy for the NP users.
You'll probably want to remove some of the permissions (e.g. access_permissions) on the duplicate policy (by unchecking them in the policy) so your users won't have too much power.
I think it will work in your version of MODX, but I'm not sure.
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PLEASE, PLEASE specify the version of MODX you are using . . . PLEASE!
MODX info for everyone:
http://bobsguides.com/modx.html