Use a public https:// URL in each Send to webhook step.
A Send to webhook step POSTs to your own endpoint. It must be an https:// address on the public internet - local and private addresses are refused.
Use the public https URL your CRM or tool gives you for incoming webhooks.
Save the automation again.
Still stuck? Send AVX-3293 to hello@theavoxai.com along with what you were doing when it happened.