How to create a (sub)folder in OneDrive web?

I created a folder First_Folder, I created a subfolder (so First_Folder/Subfolder1) with right click in the blank and I named it. Great. Now I put my files in my first folder (so I have a list of files, from which one is a folder, the rest are 30 other files), now there's obviously no blank area anymore, but that means I CANNOT create a folder (so First_Folder/SecondSubfolder) anymore?! what is that? But If I go to First_Folder/Subfolder, I can of course create new folder(s) because there's blank space, but once I put files in there I cannot?

I tried any white area: above, below, on the sides, on the border of the files, nothing, I see only this (see the picture above), while when there are no files, I see this:

Also it just took me 5 minutes and 10 "refresh" clicks to change the language, because you obviously have to open settings, but they you have to go to open the settings (inside the settings) to see the language, but doesn't matter what I choose, I still see the same language as before...so only after I deleted cache and cookies that was saved on my browser I could finally see it in English.