Dropbox asks to install word? | already installed!

Hi, I use dropbox in all my devices for some time now, with no issues; recently I am facing this situation: when I want to edit a DOCX file, I usually navigate in the folders and command to open the file, next selecting the Word app. From a couple weeks ago I can't do that in my iphone, for when I click open and select the word app, it will present me a dialog asking me to install word app, suggesting opening the appstore (which I open, just to find the word page with the "open" button, instead of the install), and latter when I click "ok" and return to the dropbox, it will tell me that eventually the app will inform that the installation is finished, but never does, and we're back to the beginning. I am using the latest ios, latest dropbox and word apps, both from appstore. Worth mentioning that the file is mine, not shared, and everything was working as it should some weeks ago; also, have removed and reinstalled word.

Any ideias?

Best regards!