It seems that an additional ID is required to access to DSWS when I try to get a token for the first time. Can I request it in this section?
It requires userID (Datastream CHILD ID) and password to get an access token.
You can use this page https://product.datastream.com/dswsclient/Docs/TestSoapV1.aspx to test your DSWS credential.
You can also refer to Datastream Web Service Quick Start for more information.
If you don't have userID (Datastream CHILD ID) and password for DataStream, please contact your Refinitiv account team or Sales team for assistance.