To download an attachment in Canary on macOS, open the email > Right click / 2 finger tap on the attachment > Click on ‘Save to Downloads’.
To download multiple attachments in Canary on macOS, open the email > Select all the attachments > Right click / 2 finger tap on the attachment > Click on ‘Save to Downloads’.
To download an attachment in Canary on iOS, open the attachment in any email > Tap on ‘Share’ icon (top right corner) > Tap on ‘Save to Files’.
To download an attachment in Canary on Android, open the attachment in any email > Tap on More (top right corner) > Tap on ‘Download’.