Hello @Plainnn,
This is pretty generic advice, but I hope it helps: you are going to want to have a common and unique key between your user profiles in Auth0 and the database where you are storing the text entered by the user. You can use the Auth0 user_id field as a unique key, though personally I prefer to generate my own unique identifier with an Auth0 rule. For example:
Whatever identifier you decide to use from Auth0, you can use a rule to include that attribute in your idToken and / or access token, which your app can then use to populate the database.