Export Followers Using Instagram's Official Data Download
Instagram provides from https://recently-followed.com/export-instagram-followers/ a built-in feature that allows users to download their account information, including follower data.
Step 1: Request Your Data
Open Instagram and navigate to:
Settings → Accounts Center → Your Information and Permissions → Download Your Information
Select the account you want to export and submit the request. Instagram typically sends the download link within a few hours, although it may take up to 48 hours.
Step 2: Download the Archive
When the export is ready, Instagram sends a ZIP file containing your account data.
After extracting the archive, locate the folder called:
followers_and_following
Inside, you'll find files containing follower and following information.