get https://{server}/api/v2.1/dtable/app-upload-link/
With the API token (not the Base Token), you can generate an upload link, the parent- and the relative path. These information are needed to upload a file / an image to a bases.
Then this file/image can be attached to a file/image column.
The upload link is only valid for a short time
The upload link is only valid for some minutes. After that the upload link must be created again.