Your first template script

const { DataRecord, DataModelEntity, Relation } = sirenapi;

/**
 * Common function for data fetching, used by all views/downloads.
 */
async function fetchRecordData(record, dataModelEntity) {
  // We can ask for a label straight away with the getLabel() method.
  const companyName = await record.getLabel();

  // We can fetch linked records using the getLinkedRecords() Record method. We should always supply
  // the maximum number of records to return, plus the sorting order for the returned records.
  const securedInvestmentsRelation = (await sirenapi.Relation.getRelationsByLabel('secured'))[0];
  const investments = await record.getLinkedRecords(securedInvestmentsRelation, {
    size: 1000,
    orderBy: { field: 'raised_amount', order: 'desc' }
  });

  // Now, given our investments we can calculate the total raised amount.
  let raisedAmount = 0;
  for (const investment of investments) {
    const amount = (await investment.getFirstRawFieldValue('raised_amount')) || 0;
    raisedAmount += amount;
  }

  return {
    companyName,
    raisedAmount
  };
}

/**
 * View function for the Record Viewer. It's responsible for:
 *
 *  1. Fetching all necessary data to display for the input record
 *  2. Building a React-based view of the fetched data
 *
 * This input object has the following properties:
 * - record: DataRecord instance for the displayed record
 * - dataModelEntity: DataModelEntity instance for the data model entity that prompted the record display
 * - render: A function that we can use to progressively render the record view
 * - cancelPromise: A promise that gets rejected when execution should be stopped (the user changes record or closes the Record Viewer)
 *
 * The returned value is the final React node rendered in the Record View > Overview tab.
 */
async function buildRecordView({ record, dataModelEntity }) {
  const recordData = await fetchRecordData(record, dataModelEntity);
  return (
    <>
      <h1>{recordData.companyName}</h1>
      <div>Total raised amount: {recordData.raisedAmount}$</div>
    </>
  );
}

/**
 * A download function.
 *
 * Like to the record view, download functions receive an input object with a record and data model entity that
 * prompted the download.
 *
 * The download function will not return anything - it just needs to start a download of the record's data.
 */
async function buildJsonDownload({ record, dataModelEntity }) {
  const recordData = await fetchRecordData(record, dataModelEntity);
  const json = JSON.stringify(recordData, null, 2);
  sirenapi.Reporting.downloadString(json, 'data.json', 'application/json');
}

/**
 * Call registerTemplate() to enable the views and downloads available in the script.
 *
 * The "recordView" property declares the view used in the Record Viewer's Overview tab.
 * The "download" property associates a file type to the associated download function.
 */
context.registerTemplate({
  recordView: buildRecordView,
  download: {
    json: buildJsonDownload
  }
});