A pop-up window will prompt you for affirmation in the transfer. If this is your to start with time transferring ETH, you might need to approve the Scroll Bridge contract to obtain your tokens. The L2GasPriceOracle.intrinsicParams getter through the implementation isn't reflected within the interface. Update: Fixed in pull request https://socialevity.com/story19834209/the-greatest-guide-to-scrollbridge