How to get SDK for Sage 50 Desktop ?

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Hi
I'm a software developer and my client uses your Sage 50 Desktop software.
I have task to add some wrapper around SDK which allow client to add data into Sage 50 from third party software. I am looking for SDK. I discovered this page : https://support1.na.sage.com/selfservice/viewdocument.do?noCount=true&externalId=119774&sliceId=1&cmd=&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl&noCount=true
 but when I install this .exe there is only documentation without any .dll files. So that link is not so helpful.
1. How can I get SDK for Sage 50 Desktop ? in the documentation I see that sdk should be free.
2. I started to study the documentation and I understand that entrypoint is : PeachtreeSession.begin(applicationId) what is this application id parameter ? how to get it ?
3. Is it possible to install Sage 50 Desktop on any free licence ? 30 day trial ? Or the only way to test it is to buy a licence for one month?

Thanks in advice for help