Is it permissible for a female student to seek assistance to join a free online educational platform, given her difficult financial circumstances, especially since her father borrowed a large sum of money and lost it, and her mother is in significant debt from preparing her sister for marriage?

The default rule regarding asking people [for help/money] is prohibition. However, it becomes permissible in cases of necessity or urgent need for which a person finds no fulfillment except through asking. Requesting a waiver of the tuition fees for educational platforms falls under the ruling of asking people; thus, it is not permissible unless the student needs this education and cannot access it except through this method.