In that case, the webhook must receive that data earlier than 1 hour before the call. E.g. receive it 1 hour 10 minutes before the call, wait for 10 minutes and send a reminder.
To share the workflow, select all nodes (or hit ctrl+a), then past the content here after clicking the button </>
Workflow for tests, that will remind 2 minutes before the call. To check - open the https://www.unixtimestamp.com/ and create a conversion, that will be in 3-4 minutes
Click on the red text below the workflow and hit “Copy”, then ctrl+v in the workflow window to past it