Hi @anon61393032,
for dispatching such triggers as a row action you have to implement custom code for the row click by enhancing the eventHandlers prop with a custom onRowClick or if preferred as additional button as a custom onEventButtonClick (see API documentation of overview engine).
You can then handle your event by calling the triggerDownload method of your attachmentHandler (e.g. the one defined for overview engine).
Additionally if you make use of A12 Clients CRUD extension for the overview keep following in mind:
Custom default row actions are not supported by the CRUD extension.
A12 Client - CRUD Extensions
Saying that means you have to implement at least the underlaying oe view as a new view container.
import { ViewViews } from "@com.mgmtp.a12.client/client-core/lib/core/view";
<ViewViews.OverviewEngineView // ...
FYI: you can also see how to general handle custom row actions in overview engine in this contribution How to make use of Custom Row Action in an Overview?