Connman actively manages content in its cache folder (means you shouldn't add stuff there when connman is running) so you need to stop the service before adding a correctly formatted profile directory and settings file and then restart the service. You shouldn't need to configure anything in iwd; the config should be passed from connman.
Note that ConnMan names the profile directory in a structured way (not plain SSID) and the SSID in the directory name and in the settings file must be a base64 encoded string; connman will not auto-convert plaintext SSID details, and since passphrase (with a non EAP) connection is the same I'd make an educated-guess that username/password in an EAP connection file also will be the same. If all else fails, the long-winded route I've seen others take for EAP connections in the past is to boot a normal desktop distro that also uses ConnMan and get the connection and config working there; then transfer the profile/settings over.