cipher - The Twenty Doors! (ROOM 6)

This is part of The Twenty Doors series.

The previous one is The Twenty Doors! (ROOM 5)
The next one is The Twenty Doors (ROOM 7)

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You go through door 5, and see a rather unusual keypad.

[♣][♦][♠][♥] [ENTER]  

The paper has been put on the left wall from when you come in, rotated by 90º.

Znw qbty zx uxtw wlb ibnsqh thygpozg nkbveni Rnn-Imed xo qjw qytjfa osa.

And, as always, a hint has been carved into the wall.

Caesar spun in a 3 width box. That's the answer to the alphabet, though the key and alphabet are reversed. And, 123456789 could well be a key, will you decipher it, we will see...

What symbol should you press?

This is the most cryptic one so far, and also hardest to decipher. I want every part of this puzzle explained!

The next door will be added when this door is solved!

Answer

My answer (sorry for my english) :

First part :

Caesar spun in a 3 width box.

So

Use rotate cipher with a 90° left rotation and a box width of 3 applied to Caesar gives you eraacs.

Then second part :

That's the answer to the alphabet, though the key and alphabet are reversed. And, 123456789 could well be a key,

So using

a Gronsfeld Cipher with a key of 123456789 and eraacs as keyword for the alphabet, remembering to reverse the keywords the alphabet

You decrypt

Znw qbty zx uxtw wlb ibnsqh thygpozg nkbveni Rnn-Imed xo qjw qytjfa osa.

into

You want to type the symbol obtained through Alt-Five on the number pad.

So the answer is :

♣