A Muslim lady who was a divorcee married a man without providing her previous divorce papers. Is her marriage OK?
Some cultures and countries insist on 'paper work'. But like @Noah and @System Down have sated, they are only formalities.
However, whether paper work is there or not, the following need to be done.
She must be officially divorced (not pending).
Shem must have completed her waiting period (Iddah). No marriage is possible without that.