Introduction to templates
Templates define the document that is supposed to be created. It describes how it looks, the data contained and where that data will appear. The template is a requirement in order to create any output with FX Reports. Given that writing a template from scratch requires some knowledge of the syntax, modifying an existing one to match your needs is a good option for a start.
A template needs a valid JSON schema as a blueprint. In that schema, allowed values and structures for building a template are defined. It specifies, for example, where columns and cells can be written or which keys and values may be defined in a format. The schema for FX Reports is defined in https://github.com/fmgarage/fx-reports/blob/main/schema/fxrp-xl-v2-2-0.json.