Manually Edit with Editor of Files in iCloud Fault

Things I have tried

I opened a file with an external Editor (like Notepad++) from iCloud and want to upload the File to the iCloud-Folder. Then I become the Note “Only Files that Obsidian can read can be uploaded”.
I opened the File with the Editor, because I can’t install obsidian on my Work-PC.

What I’m trying to do

If iCloud is installed i can upload the file. The Upload over icloud in the webbrowser does not work.