Help with Templates

I’m confused on how to use the Templates section of the admin. After entering my API key on the plugin’s admin page, I am able to choose a template from my Mailchimp account through the “Template” select dropdown. However, I don’t quite understand what the “Template Locator” field is for. It’s prefilled with the default template (std_content00).

The plugin works and sends emails correctly when I don’t have a template selected from the select dropdown but not when I select one of my templates. The email sends, but none of the dynamic fields display… instead, they show Mailchimp’s variables:

*|RSSFEED:TITLE|*
Contents:
*|RSSITEM:TITLE|*
*|RSSITEMS:|*
*|RSSITEM:TITLE|*
*|RSSITEM:DATE|* | *|RSSITEM:AUTHOR|*
*|RSSITEM:IMAGE|*
*|RSSITEM:CONTENT_FULL|*

Any direction you can provide on how to use custom templates will be helpful.
Thank you!

https://www.ads-software.com/plugins/demomentsomtres-mailchimp-immediate-send/