If you notice your Zip integration is not redirecting to the Zip login screen and you see the error shown below this could be due to either of these issues.
Incorrect API key
To be sure you do not receive this error you will need to double-check you are using the correct Zip API key in the relevant field.
Bigcommerce requires your Web-Store Key (API key) and your Public Key from your Zip Merchant Dashboard
Test Mode is Enabled
If you see the error above, it could also be caused by 'test mode' being switched on but you are using your live API keys (or vis versa)
Pleas ensure you do not have test mode enabled if you have set up Zip with your Live Zip API keys.