This article shares a possible use cases your app could support, as well as an example flow that could support the use case. You're certainly not limited to the use case, but it can be a helpful jumping off point as you plan your app's implementation.
Your app can create site members without the member signing up directly on the site. This allows site owners to create members in bulk or to import members from another site.
To import site members:
Create a list of members or retrieve the list from the external site. Structure the list as an array of member objects, ensuring that each member has a login email address. For example:
Iterate through the array, calling Create Member for each member. To comply with rate limits, ensure that requests are sent at least 1 second apart.
Call Send Set Password Email. Your app can trigger the email immediately after creating the member or allow the site owner to send it later. If the email is sent later, your app should iterate through an array of member email addresses, calling Send Set Password Email for each address.