In Japan counting floors start from 1 (one) i.e. ground floor is 一階, first floor is 二階 and so on..
The translation is correct in British English.
If it were American English (or another English-speaking country that counts floors from 1) then it would be wrong, sure. I think we can just assume the writer was British though.
Oh, especially since they also use the word "lift", which would not be used by Americans.
^笑^
In Japan, the counting of floors in buildings differs from many other countries. The ground floor is called "1F," and the subsequent floors are numbered sequentially. For example, what may be called the "4th floor" in other countries would be labeled as "3F" in Japan.
This phrase traduction is wrong.
It says "I went to the third floor", but it's the forth