CleanMyIGFeed works from the official data export Instagram lets you download. You request it once, Instagram emails you a .zip, and you drop that file into the tool. Here's exactly how.
The login below happens on instagram.com, between you and Instagram. CleanMyIGFeed has no login and never sees your password. You only ever upload the finished export file.
Log in at instagram.com, then go to Settings → Accounts Centre → Your information and permissions.
Choose Export your information → Create export, then pick your profile under Choose profile.
Select Export to device (this downloads a file to you, rather than sending it to another service).
Use these settings:
Open Customize information, and under Connections make sure Followers and following is ticked (Contacts is fine to include too). You can untick everything else to keep the file small — that's all CleanMyIGFeed needs.
Confirm and create the export. Instagram prepares your file and emails you a download link — this can take anywhere from a few minutes to a few hours.
Download the .zip from the email, come back here, and drop it onto CleanMyIGFeed. Everything is processed right in your browser.