Hello, @wbdoc
The unlimited option is for the Web Application interface only.
Automation and APIs usage have limits.
Based in your screenshot sent, you’re using a Demo account it seems you have reached the limit for automation usage (embedded). Try to send an envelope using the Web interface of your account (Login into the account, send an envelope manually), that possibly will work.
This articles explains the Automation limit for paid plans: https://www.docusign.com/iam/plan-allowances
I’d suggest to you open a support ticket to check if it’s possible increase such limit in a Demo account.
How to Open a Support case with Docusign?
https://support.docusign.com/s/articles/How-do-I-contact-DocuSign-Customer-Support?language=en_US
I hope that helps, if so, I’d appreciate your Like here.
Best,
Alexandre