I updated your post to remove your API token. You may want to create a new token just to be sure no one does anything with your account you don’t want them to
It’s been a while since I’ve done any OLEAutomation in SQL. I’ll try to set up a test to reproduce to see if I can come up with any suggestions for you.
Good news and bad news. The good news is it’s possible to use OLE Automation to make a call to an ActiveCampaign API. The bad news is OLE Automation is limited to 4000 characters (nvarchar(4000)), so if a response is more than 4K, the response will be null. Most API requests to retrieve a collection of things, like contacts or campaigns, will easily exceed the 4K limit.
If you really want to be able to make API calls from SQL Server, a better alternative would be to use SQL CLR to build a stored procedure in Visual Studio and use the HttpClient to make those API calls.
Here is a link to a SQL script of the steps I took to get a successful OLE Automation example working. For context, I am running SQL Server 2016 on Windows Server 2012.