Usually you should have the option to download the PDF file being viewed in the browser although you may need to move the pointer towards the top of the window before the option is presented (at least this is what happens when I use Vivaldi which is a Chromium based browser).
I don't use Chrome, but most browsers have some sort of preference or setting to configure under the "Downloads" area of the preference/settings page. There may be option to open files within the browser instead of downloading them, but you should also be able to select the default download location. Click on the Chrome name on the menu bar and select "Preferences" to see what options are available. You may need to look at the advanced options as well. Some settings may only be accessible by loading the correct URL in the browser to access some hidden configuration pages for the browser (I detest browsers hiding some settings this way as any settings should be fully accessible from the GUI menu).