Table Rate Shipping - Cannot Register Product or Log in for Support

I purchased WooCommerce Table Rate Shipping through my developer back in 2015. I have the Purchase Code and Date of Purchase through CodeCanyon/Envato. The plugin (version 3.6.4) is throwing an error about a non-numeric value, which doesn’t make sense. I see this message on the plugins page (under the plugin):
There is a new version of WooCommerce Table Rate Shipping available.
View version 403 - Forbidden Access to this page is forbidden. details or update now.

But clicking update now gives this message:
Update failed: Missing login credentials.

I don’t know why this is happening. And it’s infuriating that I cannot create an account or even ask a simple question without first proving that I’ve registered. But I can’t register. Though I’m sure the plugin was registered before.

In January, I found an email address (, but I never heard anything.

Please help!