Navigate to 'Templates' --> 'POS'. Then press 'Add Template'.
A POS Template editor opens. Please fill in the form 'preset'.
Create a 'Name'
Fill in a 'Tag' (is optional)
Specify a 'POS Type' (e.g., A1, A2, A4, APK, etc.)
Choose a 'Master page'
Choose a branded 'InDesign Library'
Choose a 'Format ruleset'
Please fill in the form 'sizes'.
Give up the 'Width and Height'
Give up the 'Margins'
Then click on 'Save'.
Your created POS template has been added to the general POS Templates screen.