I applied directly online and received an HR email the next day inviting me to a screening call.

The screening call was pretty basic, establishing my experience and expectations, and it went relatively pleasantly. A fair bit of the call was taken up by the interviewer talking about Stripe and selling their start-up/innovation credentials.

She informed me the next step was going over applications with a hiring manager in the United States. I then received an email a few days later saying they weren't continuing the process with me.

This would suggest to me that they don't screen or rule out applications until after the initial screening call takes place, which is a bit strange for potentially wasting both the applicant's and interviewer's time. This might be something to keep in mind if you're applying here.

What do you know about Stripe?