Hive account@hhh-fan the "missing active authority" message means you are not using the correct active key for your account. Transferring Steem Engine tokens requires you to enter the active key or the master password into SteemConnect. Alternatively, you could always use the Steem Keychain browser extension which will manage your keys for you.

Regarding the potions, the 500 charges means you have an increased chance of getting a gold or legendary card for the next 500 cards you get. The amount of the increased chance depends on which potion you buy. Basic gives +25% chance, Enhanced gives +50% chance, and Brilliant gives +100% chance. Please note that +100% chance does not mean you will get one every time, it means that you will have double the normal chances of getting a gold or legendary card.