Is "there is no supererogatory prayer between Asr and Maghrib" a noble Hadith? And if so, does it refer to the time between the Adhans of Asr and Maghrib, or between the prayers of Asr and Maghrib?

There is no hadith with this exact wording, but its meaning is correct if it refers to the prohibition of voluntary prayers after the Asr prayer until the sun sets, as stated in the hadith: "There is no prayer after Fajr prayer until the sun rises, and no prayer after Asr prayer until the sun sets." As for the time before the Asr prayer, it is not included in the prohibition, and performing voluntary prayers during it is permissible.