Unable to show file preview .pdf/.doc/.xls

Hello! I just got a new Mycloud Home 8TB to free up space on my mac. it seems to be working great for photo’s and videos, but it does not preview any documents like word or pdf.
The point of having this in the cloud is to have it everywhere without having to download it to a local drive. I am now forced to locally download it in order to view my documents. Can anyone advice?
I work on macos 10.13.3 and 10.10.5 and use multiple browsers.

Many thanks!

It depends on the web browser, if your web browser supports that file format then it would open directly in the web browser.