You have to define your ODBC connections first. Click on the Add Connection button in the Data Load Editor and choose ODBC from the standard connectors. Fill in the Create new connection (ODBC) form and save it. Then you can use this kind of connect statement:
LIB CONNECT TO 'AdventureWorksDW2014_ODBC';
I instead wish to load connection string from a config file. In my example above,
vConnString= " Provider=****;User Id=****; Password=****;Persist Security Info=****;Data Source=**** "
I am able to successfully connect using ODBC Connections defined under Data Connections. However, my intention is to load connection strings dynamically so that it could be run for different environment without any modifications to the data model script.
You can actually run the load editor in legacy mode which will forego using the data connections that you define. In legacy mode the entire script runs as it would in QlikView. I'm not sure i recommend this but its possible.
When you import the QVF app into Qlik Sense server, unless there are connections of the same name already on the server, the server will add them into the QMC. You can edit the connection from the QMC and see the full connect string. I don't believe you can use variables here however. I tried some testing (set a variable in the load editor) and reference the variable in the connect string of the data connection used in the load script... but was not successful.