Assuming you want to use Eikon COM APIs in a custom application for this purpose, use AdxRtList object and set the Source property to the name of your ATS source. Follow this tutorial and change the values in AdxRtList.Source = "IDN"; and AdxRtList.RegisterItems("GBP=", "BID"); calls to use your ATS source name, items names (RICs) and field names.
https://developers.refinitiv.com/en/api-catalog/eikon/com-apis-for-use-in-custom-applications/tutorials#tutorial-2-access-real-time-data