youSC发了个要求财产证明是什么意思？

前两天youSC给我发了个邮件，上官网上下了一个PDF：
前两段：
We are pleased to inform you that you are academically eligible for admission to the Fall 2019
semester as a graduate student majoring in Computer Science (Scientists and Engineers)
leading to a Master of Science.
To receive your official offer of admission, you must first demonstrate proof of the ability to pay
tuition and living expenses for yourself and, if applicable, your spouse and/or any children
intending to travel with you to USC for the duration of your coursework.

这个就很奇怪了，这么早要我的财产证明干嘛？academically eligible for admission是AD嘛？
有懂行情的大佬帮忙解答一下呗？
P.S. 财产证明一定要冻结么？储蓄行不行啊

补充内容 (2019-1-11 15:58):
文件里也没有DDL，很懵B