Report Templates are not necessary to begin a report in PlexTrac, but they perform two very useful functions:
They allow you to pre-populate your report with pre-filled sections of a report, such as Introduction, Methodology, Threat Model, etc.
They allow you to link a custom export template, so that your final .docx is exported into a document that is branded for your business in a manner that suits your reporting methodology
You can choose one or both of these options when creating your Report Template; you do not have to do both. Additionally, you can change the custom sections or the export template at any time - even after you have completed writing your report.
For specific sections titles and Custom Report Fields needed for your report, please reference your Jinja code or the Readme provided that details the requirements.