Start from something close.
Each template opens in the editor as your own draft. Change the dates, rename the milestones, tick through the checklist items, publish it, and send the link. Nothing here needs an account.
Nothing here fits?
Describe what you're planning in a sentence — "launch a podcast in four months", "pack for Japan with two kids", "turn this dinner into a recipe checklist" — and the editor will draft the artifact for you. Then edit it like any other draft.