Thank you for reaching out to the Community and @webdew for your input!
The Forms tools should be available for free accounts as well. I'm wondering if you tested the API with a new HubSpot account - our automated systems sometimes require additional account verification before a new account is able to use Marketing and lead generation tools. If this is the case, you've probably seen a notification in your account with a request for more information. This could be one of the reasons why the account doesn't have access to the Forms tool.
Additionally, it would be great if you can check if you've used the right account ID and the API key. The Portal ID is usually a 7- or a 8-digit number, without spacing or other signs.
Another thing to check are the required parameters to send form submission data to HubSpot, especially the Legal consent options if the GDPR functionality is enabled in your account.
If you're still getting an error after checking what I mentioned above, it would be great if you could send us more information about the API you used and the error response you received (examples here). The more data & screenshots you share, the better the Community can help!