Postamatic runs based on your Spreadsheet Settings and your Language associated with your Google Account. Getting these set right is imperative.

Spreadsheet Settings Overview

Click File > Spreadsheet Settings and you'll see a popup like this:

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  1. Locale- determines how Google Sheets builds Functions and time date formatting. Make sure this is set for your country.
  2. Time Zone - This determines when Auto Posting will Run.
  3. Display Language - This controls what laguage POstamatic will build it's interface and messaging with. Postamatic supports the languages that Google does, and this is the setting that will control which language the tool runs with.