wa alikum al-salam
Hadile, I'm not sure I got your question right. Maybe you would like to rephrase it a bit? I'll try answering based on what I understood.
You uploaded a file into a Moodle course and that file was saved at filedir/20/5f/... and now you want to download it from the Moodle course? If that is the case, you needn't worry about where the file is saved, because that is very technical information and users do not need it. Moodle knows how to handle files, where to save them and how to find and retrieve them. So once uploaded, you can download the file just by right-clicking at the link that was created for the file at the course, and choose the "Save as..." option.
If you want to upload files so your users can download them easily, you may want to consider using the "File" or the "Folder" resources:
https://docs.moodle.org/28/en/File_resource
https://docs.moodle.org/28/en/Folder_resource
The following pages might be useful:
https://docs.moodle.org/28/en/Resources
https://docs.moodle.org/28/en/Main_page