Thus if I have to answer your question directly, then the answer would be that that Kendo UI for Angular doesn't support adaptive cards. However, the developer is able to add any custom HTML and/or CSS within an Angular ng-template. Indeed, we try to provide such templates in all Kendo UI for Angular components in order to allow the developers to customize certain parts of the Kendo components. I assume that you need to use the adaptive card library with the Kendo UI for Angular Conversational component. If that is the case then please check how to define a custom message template for it at the following article:
That feature allows to add an adaptive card, or any other content, to it. For example please check the following demo demonstrating how to nest an adaptive card within the message template of the Covnersational UI: