The option to add repetition to a to-do is revealed under the due date field in the detail view after you've picked the first date in the series.
“Hi Al & Mark,
Really sorry to hear you're running into that issue! We're looking into how to better handle that scenario where one email address shares two account types.
We're also working on getting the toggle deployed worldwide as soon as possible. It's taken a bit longer than expected and I truly apologize for the delay!
“Hey there Peter,
To-Do Preview is currently available to organizations with Business Essentials, Business Premium, Enterprise E1, E3, and E5. We hope to expand this list as time goes on. As support for Microsoft personal accounts comes standard with all To-Do apps, naturally users with Office 365 Personal and Home have access as well.
“Hey there Blake,
Office 365 subscriptions are only required for login with work or school accounts. While we do plan on offering these customers additional features in the future, using To-Do with a personal Microsoft account or with an additional Office 365 Personal or Home subscription will suffice :)
To-Do currently uses the Outlook Tasks API so the to-dos you see in one app should reflect what you see in the other. We're hard at work on further integrations like calendar support and so on, so stay tuned!