Thank you very much for your request!
I've checked iOS and Android to see it works in the two platforms, but not the web version, which we'll take some time to fix.
Sorry for the problem and please turn to the mobile phone version for the present.
Nice day!

I can add the file, but when open the file in the app doit.im opens a white window without any content!

@federicosaxo Really sorry for the problem! We've submitted it to make it fixed.
Thank you for your understanding.
Nice day!