I tried using the SOAP API to create a data extension and set the CategoryID to the Salesforce Data Extensions folder, but I get this error:
"Unable to save data extension into a non-data extension category. The category provided was of type salesforcedataextension."
I opened a case with support who also said there is no SalesforceDataExtension object, allowing me to create one.
So I also tried to first create a data extension in the regular data extensions folder, then use InvokeUpdate to change the CategoryID, but that gave the same error. Has anyone found a way to do this? It seems the SOAP api is mostly concerned with adding columns/rows, not changing DE properties. Hoping there is something new that someone has discovered.