If you need to automatically download SQL script from Redgate Data Modeler, for example, for the purposes of your build system, you definitely should check out our Redgate Data Modeler API. It allows you to download an SQL or XML of your model by a simple HTTP request. In the command line, it may look like this:

VERTABELO_API_TOKEN=put-your-api-token-here
MODEL_ID=put-your-model-identifier-here

curl -u $VERTABELO_API_TOKEN:  \
        https://my.vertabelo.com/api/sql/$MODEL_ID  > create-database.sql

To learn more about Redgate Data Modeler API, go here.