How to use WIX SPI to add new Ewallet payment provider

Question:
How to connecting store to ZainCash, an ewallet payment provider using SPI

Product:
[Which editor or feature is your question most relevant to? Wix Editor]

What are you trying to achieve:
Im trying to use Payment SPI to add new Ewallet payment provider called ZainCash, who offer connection through API, documentation https://docs.zaincash.iq/.

What have you already tried:
I have followed the instruction in :

But not everything is answered in this example, and its for payment gateway, not sure if its different the Ewallet.

Any assistance to do this integration will be appreciated. Not many documentation or videos available on this subject

Additional information:
[Include any other pertinent details or information that might be helpful for people to know when trying to answer your question.]

Do you have a specific issue or thing that isn’t working?