Hi @saladgoat,
Thanks for posting on the forum.
The 10002 error is either that your Paypal API details are wrong or you have it in Sandbox mode using live API details. Or in Live mode using Sandbox API details.
Make sure you are using the correct API keys. check that there are no spaces before or after the API keys.
Are you using sandbox mode for paypal? you will have 2 different API keys with paypal.
You will have 1 for live mode & a different 1 for sandbox (you will have to create a sandbox account for a sandbox API key)
Please double check the API details & credentials for both paypal.
Kind Regards,
WPMU DEV