Looks like Scarlet can only install a .ipa file which Construct can't create. You'd need a Mac (either physical or in the cloud) to create the .ipa.
But if you have access to a physical Mac, you can export from Construct as an Xcode project, then install directly onto your iOS device (first time needs you to connect the iOS device to your Mac via a cable, subsequent installs over local network). If you have access to a Mac in the cloud, you won't be able to connect with a cable, but can deploy to iOS devices via TestFlight.
TLDR - you need access to a Mac - and if you have that, you don't need Scarlet.