Generally available for ConfiForms form administrators with Confluence admin permissions and for users who are Confluence space admins of the space where this form is located
Direct link to Import API is: http://CONFLUENCE_SERVER/confluence/confiforms/import.action?pageId=PAGE_ID
PAGE_ID is the id of the page where ConfiForms form is configured
And supports CSV formats for data importing.
To start with data importing you need a ready ConfiForms form as the importing API expects you to set the mapping between columns and ConfiForms fields.
If your confluence server runs in a root context ("/") then the URL will not include /confluence