I don't see any problem. I uploaded few files. The folder was created and all files were uploaded into one folder. No issue. I also try to create folder manually and upload it there. Files were uploaded there.
Right click and report any upload from my app directly. I can try to check logs.
Ok, but how do I use it? Where do I get the folder ID?
Edit:
Ok, I tested it, and it looks like I just need to enter a folder name, not an ID. But there’s still a problem: your program doesn’t use the existing folder. Instead, it creates a new folder with exactly the same name and uploads the files there.