When creating a New Knowledge Base with GeneXus Next Desktop, you can select 'GeneXus Prototyping Cloud' in the Prototyping Target combo box.
Then, the Data Source combo box will be set automatically to 'Deploy To Cloud'.

Note that the Data Source can't be changed there.
PostgreSQL is used by default (for both .NET and Java) to facilitate the use of Embedding data type, which is temporarily available only for this DBMS.
To configure another Data Source, go to the Preferences window, and at the Environment level use the DataSource property to set another DBMS.

1) 'Deploy To Cloud' is not working when generating with Java.
2) In the future, it will be possible to change the Data Source in the 'New Knowledge Base' and 'New Environment' dialogs.