What software/tools do you use to scrape tweets under a certain hashtag?
Use Trackmyhashtag. It is a free & paid Twitter analytics tool which can help you track any hashtag in real-time and also enables you to scrape Tweets for any hashtag for any time period since 2006.
You can simply visit the website and click on 'Historical data' where you'll find a form which you need to fill with your required details.
Within an hour, you'll get your Tweets data associated with other details.
Thank you :)