The reMarkable size is a screen size, not a standard paper size. It may not print or export cleanly onto Letter or A4.
Accounts are invite-only for now, so contact the site owner to get one. You don't need an account to use Notesofast though: your notes live in this browser and stick around for as long as the browser keeps its data, so it works fine as a local scratch canvas. You can also export a notebook as a PDF to keep a permanent copy.
If writing with an Apple Pencil, there is a known issue where every second pen stroke will not register at all. To fix, turn off Settings › Apple Pencil › Scribble.
One finger pans, two fingers pinch to zoom. Zoomed out to a
single page, swipe sideways to flip pages. A two-finger tap
is undo, a three-finger tap is redo.
Currently, using touch input to draw is not supported. A
stylus or mouse input is required.
Everything is saved locally in this browser (no account required). Clearing your browser's site data or using private browsing will remove them, so export anything you want to keep. With an account, notebooks also sync to the server and across devices in real time. Notes are stored locally in OPFS (unencrypted, but inaccessible to other sites) and are encrypted in transit and at rest on the backend. Notes are NOT end-to-end encrypted.
Notesofast works offline and can be installed to your home screen as a web app (Share › Add to Home Screen on iPad, or the install icon on desktop).