DriveFS | A google drive fuse filesystem implemented in C++ | File Utils library

I'm making a PoC app that will deal with uploading a vast amounts of data to Google Drive via their File Stream app (DFS).

The subject of my concern is how the File Stream deals with uploading the files specifically. Upon my research, I gathered that when you copy the file to the Google Drive (I mean the file system, typically G:), it is actually copied to the application's cache (typically %LOCALAPPDATA%/Google/DriveFS), where it sits so the app can do all the uploading. That's fine, and it is also logical that when you want to copy, say, 100 GB of data while having only 50 GB of disk space available it will scream for more disk space. However, I still want to upload these 100 GB. Obviously, the solution is to split it into chunks and then copy them accordingly, but here is my question: how will I be able to know if the DFS finished uploading the previous chunk, so I can then copy another?

I made some experiments with uploading two ~2.5 GB files, starting the upload with a couple of minutes interval, so that I can inspect the DFS cache's size and it roughly matched the expected: before anything it was a couple of MB, after I copied the first it rose up by about 2.5 GB, after the second it rose again by the similar amount. Everything as expected. Now, I anticipated that after it was done with uploading the first file, the cache would shrink down again by the file's size, but to my surprise - nothing changed. It stood adamant, even after the second file finished. So that's where my question comes from - How would I go with uploading the data chunk by chunk? I really, really don't want to call the GDrive API to see if the files were uploaded; I'm using the DFS so that I don't have to include any authorization mess into that.

Any insight will be helpful. Oh, and I'm developing this is Python, but this is not entirely relevant to the question.

So I'm making a kind of like a telltale game using readonly inputs. I'm using onfocus to call a javascript function, but it won't run the function. I'm new to stackoverflow so if you can't see my code, please tell me. Also, I'm coding on Chromebook so the links to the CSS file and JS file are drive links.

EDIT: I think this is a problem on my computer's end since it's working perfectly fine when I run it on here.

EDIT 2: MY GOD I'M AN IDIOT! I misspelled something in the javascript section, something that DIDN'T EVEN MATTER TO MY GAME was MISSPELLED.