If I remember correctly, the Salesforce connector uses an OAUTH flow to handle authentication and authorization.
In order to set this up, the process will look like this:
- In your SalesForce enviroment, create an application ID and application Secret for your Mendix app
- In your Mendix application, enter these credentials, (and make sure to encrypt them before you save them)
- In the SalesForce configuration, you will probably need to provide a callbackURI, This is used to inform the Mendix app that authentication was successfull (or unsuccessful)
In order to direct back to the Mendix app, you can use the deeplink module. (Documentation)
These pointers are meant as a guideline, I hope that the documentation I provided will get you started.
This forum post was about a similar issue.