Hi @DishaSharma ,
In order to send the Communication like email, SMS , Push and other channels using the Custom Schemas Data (Non Out of the Box Schemas Data), we require to create a Target Mapping and map the same in the Delivery Templates or any Deliveries.
For Out of the Box Schemas, the default Target Mappings are already provided.
Also, Please find the documentation link to check the steps to create it.
https://experienceleague.adobe.com/docs/campaign-classic/using/configuring-campaign-classic/use-a-cu...
Regards,
Pravallika.