Hello @phallinijupudi - In this case, you need to first capture the user details once user clicks and start your job.
Afterwards, once the job is completed, you can sent proactive notification to that particular user.
Reference doc
https://learn.microsoft.com/en-us/microsoftteams/platform/bots/how-to/conversations/send-proactive-messages?tabs=dotnet
Reference sample:
https://github.com/OfficeDev/Microsoft-Teams-Samples/blob/main/samples/bot-proactive-messaging/csharp/coordinate-logger/Bot/CoordinateLoggerActivityHandler.cs