What does it mean to send me a transfer receipt on Alipay after the installment is overdue?

Because you logged in with the mobile phone number bound by Alipay.

A receipt is a voucher issued by a student loan account or an enterprise account after paying a certain amount of money through Alipay, which is called a receipt. Then the number filled in this receipt is generally the loan university number or enterprise number, which is different from Alipay account number.

Receipt is a form used when the other party receives the reply or written notice of your goods, that is, when some individuals or units send notices to other individuals or units, in order to ensure that the individuals or units that need to receive these notices or messages know these notices or messages, the individuals or units that need to receive these notices or messages will reply.