To answer your questions here: It's a webapp, designed to work fast and clearly on desktop and mobile.
When not signed in, there's a prompt to join next to the Download and print button. Perhaps I should make that more prominent.
The download options are so you aren't locked in if you create a list. There's no checklist standard txt format, so I provide lists in Markdown or JSON, take your pick.
Seeing the download options was really reassuring. It did clearly address my lock-in concerns / worries about having to re-type everything into a new app :)
Looking at it again you do have screenshots of 3 phones near the top of the page. I think I kinda ignored that because the rest of the page didn't talk about that. I'm gonna blame my mental "ignore in-page advertising" filter for not really noticing the screenshots.
Maybe have screenshots under the 'create/perform/schedule/delegate' items too, so it's clear that you're using an app to do all this? (And what the app looks like, and the UI / UX it provides?). I myself dunno, but good luck with this, and thank you for listening to our feedback!