Queries on licensing of Dynamics 365 for Field Service: Resco Woodford solution

During demo preparation for customer on Dynamics 365 for Field Service, we found that for the following purpose:

1. Designing/customizing/running Field Service on mobile app

We must install RESCO client, although in the following link: https://www.microsoft.com/en-US/dynamics/crm-customer-center/install-the-field-service-mobile-app.aspx

“To customize Field Service - Dynamics 365 (mobile), you need to install the Resco Mobile Dynamics 365 Woodford solution. This lets you configure mobile behavior around your business needs. If you don’t need to customize the app just yet, you can use the default field service mobile configuration.”

 In fact, Field Service on mobile cannot run without RESCO client pre-installed. So, I have a problem about:

1. On Microsoft product policy, do we really need to install RESCO client for running Field Service on mobile platform?
2. If “Yes” for #1,in what case that Field Service on mobile required a RESCO client? What kind of licensing of RESCO needed?

Please help me clarify these information

Thanks for your supporting.