If his first two marriages were not Catholic sacramental marriages, then there is nothing to annul. The Catholic Church does not recognize civil (law) marriages. His marriage to Melania took place in an Episcopal church, so it is not a Catholic sacramental marriage. Salvation’s earlier reply claims that Melania never received First Communion. If true, that would seem to answer the question. There is too little information to determine with certainty if Melania can receive Holy Communion.
I have personal experience with an annulment. It doesn’t make any difference whether the previous ones were in a Catholic church or not in a church at all. I was born into a Baptist family, had a just out of college marriage that was a disaster, had to get an annulment, take RCIA, have first communion, get confirmed, and have a marriage ceremony in a Catholic Church. There is a little different process if a Catholic is married outside of a Catholic Church. In that case, the marriage isn’t recognized at all by the Church and it is just an administrative matter, no need to prove invalidity for an annulment. That is where people get confused. Even a civil marriage between two non-Catholics is assumed valid unless proven otherwise by the Tribunal.
Therefore, even if she was confirmed, she can’t receive, unless DJT was able to get the previous ones declared null. At the time my wife and I were married, we were in our 30’s, went ahead and got married, got the annulment (which was cut and dried in my case) and had a convalidation of our vows. My wife could not receive communion till we did that. We don’t know if DJT had anything sent before a marriage tribunal, which is the only thing we would need information on.
That said, I’m impressed by her actions, and she seems to have an authentic faith and reverence that is lacking in a lot of people.