This is the full Installer.app wizard.
Guitar Tuner tunes guitars, bass guitars, and pianos. The first week is free. After that, redeem a code or pay CA$1.39 once (US$0.99 at the Bank of Canada rate). Sold from Canada.
What this wizard does:
Your free-week clock and unlock stay in Keychain, so reinstalling does not create a second trial.
Click Continue, choose the disk, then Install.