When you login to Applai Chat, you can go to settings and find 'Integrations'. Here you can pick from a list of sources.
When you select Notion, you will be taken through a setup flow, asking you what data in Notion you want to give Applai Chat access to.
Once you have decided what data Applai Chat should have access to, it can use it as a data source for your questions.
It will even link to where in Notion the data that provided the answer is coming from.