Try typing in file:/// into your browser, that should open a navigation page where you'll have to dig into your phone's file structure to find those downloaded txt files. (On my phone file:///storage/emulated/Download will take me to my browser's Download directory.)
But this won't give you any ability to do much at all with the text file itself (edit, rename, etc.), using a browser for this is basically just a viewing. A file manager app really is more versatile and will give you more options.