In the app's Settings add an email address for parsing. All flights that are recognized will be added automatically to your flight feed.
The IMAP option is for accounts with custom domain names, or are for iCloud. Note: If you want to parse flights from your iCloud email, connect it via IMAP, not the iCloud button.
Go to Settings.
And connect your IMAP/Gmail/Outlook etc. accounts.
Go to Profile > tap on a three-dot button at the upper right corner > Settings > tap on "Import flights" button.
Now you can connect your account.