Complete error description: Error 404: The login failed, what should I do?
Sometimes, the connection between Nembol and WooCommerce keeps failing because there are block functions active on your Woo website, which rejects the connection with Nembol as a third-party app.
In this case, you should:
Turn OFF your Anti-spam filters.
Switch OFF the WooCommerce firewall, and retry with the whole login process explained above.
If even deactivating the firewall, you’re still not able to connect WooCommerce to Nembol, ask your domain provider to whitelist Nembol and retry.