In accordance with Android Police, the built-in download Android manager does not manage downloads made through Chrome. The last version Dev (Chrome 50) finally allows you for the first time to pause and cancel downloads.
So if you are trying to download via Chrome a archive PDF, or MP3 and you need to stop it for any reason, now you can.
To be able to do this right now, you should use the somewhat problematic trial version Chrome Dev and your mobile should be running marshmallow or later version.
If you've already downloaded Android N OS to try it out, you'll find that it works there too, but by default downloading different types files it's done by different mechanisms so you shouldn't get confused if different download apps open.
If you do not want to install the Dev version of Chrоme on your phone again, you will have to wait until the next stable version comes out.
Of course, there are other Android browsers like this Opera which already allows you to pause from 2014.
