请问receipt from the test centers是什么？

0417AmyUID: 3881372

学校要求雅思6.5，现在只考出6.0，问学校最晚什么时候提交语言成绩，学校说：

“About your English requirements, I don't know the exact date for uploading your results. But when applying for the master program, you must either upload your result or a receipt from the test centers confirming, you have signed up for a test. ”

这个receipt到底是什么？是报名雅思考试之后的那个pdf准考证吗？还是什么？从雅思报名网站哪里可以下载？