The second screenshot shows that you've downloaded iOS 11.4.1 to your device but have yet to install it. Do so by clicking the blue Install Now link. You should then be able to install the current version of iMovie for iOS.
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The second screenshot shows that you've downloaded iOS 11.4.1 to your device but have yet to install it. Do so by clicking the blue Install Now link. You should then be able to install the current version of iMovie for iOS.
tt2
Can’t download iMovie.