Do the conditions for acting upon a weak hadith apply to the hadith: "Whoever prays six rak'ahs after Maghrib, not speaking ill between them, they will be equivalent to twelve years of worship," so as to act upon it?

This Hadith is very weak and does not meet the conditions for acting upon a weak Hadith. Its weakness was stated by Al-Tirmidhi, Al-Bukhari, and others. However, there is no harm in performing supererogatory prayers (Nawafil) between Maghrib and Isha, as long as one does not believe they are specifically attributed to the Prophet, peace be upon him. Indeed, there are Hadiths that affirm the permissibility of enlivening this time with prayer.