API call Datasets Get Tables DO NOT WORK

As lbendlin has said, it seems like you're using the Push Datasets API, which won't work if you're using just a "standard" dataset.

If the dataset resides in a workspace assigned to a Premium (or Embedded) capacity, you can use the Tabular Object Model (TOM) or the ADOMD .NET Client Library (that one is .NET Core, but there are .NET Framework versions) to speak to the underlying Analysis Services (AS) model through the XMLA endpoint. You can see this blog for an example on how to query measures for an AS model - it's an example using Azure Analysis Services, but the same logic applies to the Power BI XMLA endpoint. It's also querying measures, not tables - but the same logic applies.

If you're not using Premium/Embedded, your options are a bit more limited. One far-from-ideal way to get the Table names would be to unzip the pbix file and look in the DiagramLayout file, which lists all the tables in the dataset. But without knowing what exactly you're trying to do in your scenario, I'm not sure whether that's a feasible solution.

Hope this helps,

Ed