PropelAuth offers a flexible system for collecting custom user properties, enabling businesses to gather various information from their users, such as how they discovered the service, their acceptance of terms of service, or specific metadata like a Stripe Customer ID. By defining user attributes, businesses can choose to collect information during signup, on the account page, or require it before product usage, and the platform ensures that even manually onboarded users comply with necessary agreements. PropelAuth also supports the integration of SAML for enterprise customers, allowing automatic collection of certain user data during login with work credentials. Additionally, the system allows for the creation of non-user-facing JSON fields for storing data that users cannot see or modify, further enhancing customization and data management capabilities.