How would one do Onboarding?

I’m new to Alpaca. I’m looking at this API and others to fill a solution for an app I’m developing. I want to be able to sign users up natively through my app so they can make investments through my UI. I didn’t see this as something possible on the Alpaca API page. Though it appears to be something offered by DriveWealth. Just curious if I’m missing something, any info would help!