在PHP中，move_uploaded_file将文件上传到一个目录，但无法上传到其他目录？

I am relatively new to PHP, and am working on a website which should accept functionality for when user's upload pdf, doc, or docx files. I was able to look up code online and see what the html form looks like (not my code, as I am simply trying to see if bare functionality for uploading works right now) and also the code for processing the upload. I will put the codes below, and I don't think there's anything wrong with the code itself, but maybe something to do with permissions for the directory I'm uploading the files to. I am relatively new to PHP, and am working on a