Read the error carefully! - it says that the platform and browser are not valid. So that means the ones you have provided are either spelled wrong or do not exist.

Go to browserstack and look at the list of available devices they have and make sure that they match exactly to what you provided in the options object.

You can also use this capability generator that allows you to experiment with what they have -> https://www.browserstack.com/docs/app-automate/capabilities