You can easily create a WordPress user via Zapier by using WP Webhooks Pro (WP Webhooks uses the same structure. The only difference is, that you can’t update the user meta). The structure is super flexible and easy to adapt. For more details, check out the video down below.
This plugin will enable you to create a user with all available attributes from the user object.
Also, it is possible to create custom user meta with the very same webhook. An explanation for that is also included inside of the video.