I need to link an App to my Adobe Sign account

I've been unable to reach you through chat. I have a standard user account to Adobe Sign which we want to link to an outside App we will be using to register people to our organization (which is a Non profit ONG, a union). The App has been programmed but it seems that our account doesn't allow this type of things. I need to know what can we do to enable this app to simplify our work.

Basically, the App is linked to a web page form in our website that automatically sends a document to the person who registered  to the email provided for him or she to sign its reception, basically.

Can you please help me? I've been unsuccessfully trying to get help for weeks; I live in Chile and cannot do international calls.

Thank you.