You've reached the maximum of 10 saved drafts. Delete one to start another.
The "Create template" wizard saves your in-progress work as a draft automatically. Up to 10 can exist at once per Switchboard - delete one from the Templates page to free up a slot.
Go to the Templates page.
Delete a draft you no longer need.
Start your new draft again.
Still stuck? Send AVX-3029 to hello@theavoxai.com along with what you were doing when it happened.