Hi @AdapterTest. No such thing as a silly question here.
You are correct! On the dev environments page you’ll need to name your environment, and where it shows ENV_NAME in the sample URL you’ll want to replace that with whatever you’ve named your environment as.
For example, I use prod as my dev environment name, so my URL looks something like this:
https://api.twitter.com/1.1/account_activity/all/prod/webhooks.json

Hamza