If you upgraded to v10.3+, and have had issue like this
while trying to add marketplace modules to your project,
This would most probably mean that you'll have to configure Gradle (the tool we use to build and manage Mendix projects) to access custom repositories.
Please refer this documentation to know how you can configure your own custom repository in Studio Pro.
Why should we do this?
The setup you are currently on is probably not connected to the internet or has limited/restricted access to the internet. This configuration will allow you to access only the required resources from specific trusted locations/repositories without the need of having access to the entire internet.