Make sure the version you downloaded is the smartphone version. If you're running it in the RPG Maker MZ emulator, try other emulator options as well. If you're on a computer, you should download the Mac or Windows version; just unzip it and open the .exe file
If you can read the game’s initial message before the error appears, follow the instructions in the message: download a video codec for your device—the most popular one is the K-Lite Codec Pack—and install it so that the animations will appear in your game.