cipher - The Twenty Doors! (ROOM 3)

This is part of The Twenty Doors series.
The previous one is The Twenty Doors! (ROOM 2)
The next one is The Twenty Doors (ROOM 4)

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When you finally realise that the cipher used in room 2 was the Bifid cipher, you come into the next room. The first thing you see is some paper:

R28gYmFjayB0byB3aGVyZSBpdCBhbGwgYmVnYW4u

Next, you walk forward to take a look at the keyboard. This one is a normal keyboard. Then you turn to look at the wall, and, as usual, there is something carved into it: I was involved with making email attachments possible.

Hmm... What could this mean? Well, you have not died yet. You may as well try.

HINT 1:

So far, everything up until the point where the first room is entered is correct. You will have to dig deeper to find what's hidden in there.

HINT 2:

A certain edit I made may be of importance...

HINT 3:

Bob has found the final cryptogram of this door, so now all that remains is to decipher that code!

HINT 4 (REQUIRED TO SOLVE):

I halved the bottles standing the wall.

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

Answer

Translating the text on the paper from Base 64 gives you

Go back to where it all began.

Go to Room 1 and look in the source. You see a message:

The profile of the evil guy who began all of this may hold something interesting...

In the OP's profile, you see the message:

TidoTt ilhurr om hnysS saieqeofR fee res gs edwo 3o wDore"ee.r r ToiL"

Decoding it with a

railfence cipher with 5 rails

Reveals that

The required word for Room 3 of The Twenty Doors Series is "Legalise".