By default and as a recommended practice, only users with the Salesforce System Administrator profile are permitted to upload a template from their local hard drives. This feature is always enabled for administrators because of its utility in creating and testing templates. The Composer Administrator may enable this feature for all other user profiles as per your business use case. You can then upload your local template to merge and download/email the document.

To use a Local Template

  1. Click the Composer Solution Button. 
  2. Click the Local Template tab.
  3. Click Select File and upload the template.
  4. Click Preview if you want to preview the document before the final merge.
  5. Click Merge & Download or Merge & Email as per the composer solution configured.

For more information, refer Using Composer Button and Using Composer Lightning Component sections.