How to enable API access on a Salesforce account (in Salesforce Classic)
This tutorial is for Salesforce Classic, if you are using Salesforce Lightning, please navigate to this article.
After installing the Record Validation for Salesforce package, you need to enable API access to your Salesforce environment.
As part of configuring Record Validation for Salesforce, you need to enable API access to your Salesforce environment by profile or permission sets. You will need it when working with Record Validation!
Enable API access in Salesforce by profile
Navigate to (Salesforce's) Setup - Manage Users - Profiles
Click 'Edit' for the profile you want to update.
Scroll down to 'Administrative Permissions'.
Check the 'API Enabled' box.
Enable API access in Salesforce by permission sets
Navigate to (Salesforce's) Setup - Manage Users - Permission Sets