Thanks for the reply.
"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."
Yes, I did read this elsewhere. But I did post the correct password. I also checked and tried it out elsewhere several times.
Thus remains my problem what I have to/should do.
As said, I won't install and use chrome to install the Steem Keychain browser extension - unless someone tells me it works on brave and/or dissenter browser too.

"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. "
Okay, thanks for the information.
This does the situation make a bit better.
"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."
And this was crucial and changes it a lot.
Ah, yeah, then it is fine. No further questions here.