"They cannot meet you today."
Translation:De kan ikke møte deg i dag.
It can help to think about whether you would use 'I' or 'me' in the same context.
If you would say 'I', then the equivalent for 'you' is 'du'.
Eg: I am reading = jeg leser; you are reading = du leser
If you would say 'me' then the equivalent for 'you' is 'deg'.
Eg: they cannot meet me = de kan ikke møte meg; they cannot meet you = de kan ikke møte deg
It's confusing because in English there is only one form for 'you'.