What are the Instructions on how to determine which permission a role is missing?

My problem is that when I try to perform an action (in my case a REST API request to get a list of customers)

'use strict';
const NsApiWrapper = require('netsuite-rest');
const NsApi = new NsApiWrapper({
 consumer_key: 'aa',
 consumer_secret_key: 'aa',
 token: 'aa',
 token_secret: 'aa',
 realm: '12345',
 //,base_url: 'base_url' // optional
});

NsApi
.request({
 path: 'record/v1/customer/',
})
.then(response => {console.log('response is:', response); return response.data;})
.then(data => console.log('No ERROR', data.links))
.catch((err) => console.log('ERROR', err));

I get a rather terse message about a missing permission, namely on the integration record's page I open the Execution Log tab → REST Web Services and there download a JSON file for the response.