Multi Threading for a crawler in Prefect

I have a crawler that is currently working with IIS. I want to switch the orchestration to prefect. I was using threadpoolexecutor. I have a free version of prefect. I tried to implement the same code with task and flow in Prefect but it is not working. I want to split the tasks between browsers, I want to open 5 browsers, each browser will do individual crawling and then send back the results to my list. Any ideas how can I implement it?
@anna_geller