Notaku needs your root page to be public to be able to sync with Notion, to make a page public you need to click the “Share to web” button.
Then you will just need to copy the url and paste it in the Notaku dashboard.
Notaku supports most of the Notion block types, you can find a list here
In case you need help you can read the Notaku documentation or reach out on the Notaku site live chat.
You can add pages in Notion and they will be displayed on your Notaku site on the sidebar. There is no limit on the nesting level.