Setting Your Authorize.net API Keys
1. Go to the website and login to Admin
2. Go to WooCommerce > Settings > Payments
3. Check “Enable this Gateway”
4. Go into your Authorize.net account and get your API keys.
Note this is from Authorize.net’s website directly (if this doesn’t work anymore, then go to Authorize.net’s website and see if they’ve changed… Read more of this article