Is it permissible for a 14-year-old girl who has memorized the Qur’an to create a YouTube channel to publish anime clips set to female vocal nasheeds (by the artist Emi Hatory) that are free of musical instruments, knowing that a woman’s voice is considered awrah (private/exposed), and can she add a disclaimer "males are not allowed to enter" to these clips?

If anime is free from Sharia prohibitions, then there is no objection to publishing clips from it, provided copyright is observed. As for a woman's voice, it is not inherently awrah (something that must be concealed), but it is not permissible for her to soften it for non-mahram men, based on the Almighty's saying: "Then do not be soft in speech, lest he in whose heart is disease should covet." Therefore, it is not permissible to include a woman's chanting in clips accessible to everyone, and merely writing "Males prohibited" is not sufficient.