Hi @jialin.yang , welcome to Bitmovin community. Bitmovin player SDKs do not support Ads + Casting use case out-of-the-box. The expected behaviour of player is to not play Ad on sender device when connected to casting receiver. The default receiver will only play main content.
If you wish to playback Ad on cast receiver, it should possible to implement this in a custom CAF receiver application. You can forward the Ad config/tag information from sender to receiver using Bitmovin config and then read the same in CAF received LOAD request. You can find more information about sending custom data in Send custom metadata on a custom Chromecast receiver - #2 by lucky.goyal
Then you can use the Ad config/tag to configure Ads directly in receiver code.
Please let me know if you have more questions.