The Replicator requires a layer of blue tape to cover the build platform before you can print. You should find the tape hanging with the filament colors above the printer. If there’s already a layer on top of the platform, and it doesn’t have any tears or large blemishes, then it’s ok to reuse it.
Otherwise, you’ll want to cover the platform in strips of blue tape, ensuring that none of the acrylic base shows underneath. This will ensure the print sticks.