You need to use the DataDictExporter that is in the ..\Softrak\System folder pointed at the sample data and export the "table and field names" to Excel

...\Softrak\system\DataDictionaryExporter.exe /ODBC /A /H

The ADS Alias tag is what ODBC uses to access the data not the Windows "File Name". For the General Ledger all Alias's begin with AL90D.

Select * from AL90DPST_PST should work for your query, the extra _PST is required because the same table definition is used for multiple files.

You should also edit the DSN Table Selection to choose

AL90DMST |AL90DBUK | AL90DPST | AP90DGLO

you will be shown only the tables of interest

I always suggest using Excel or MSQuery to make some initial probes into the data