The first warning is used for the project having numerous amounts of assets. Which could crash your computer. If on your device, your done. The second warning is exclusive blocks. Which means the blocks from TurboWarp and/or PenguinMod will not work on Scratch. The third warning is actually Widescreen. This project includes Widescreen. (640x360) It means that you can't see the project fully because Scratch is only (480x360) Hopefully they can change it in Scratch 4.0.
These warnings will first appear on the full version of Scratch Cat and Dog Adventure in November. @MasterZenoUltimate