Hi Giulia Caldaronello

If you feel you have a Language Cloud Account and your purpose is to access Machine Translation then this can be done in 1 of 2 ways:

A. Without out an app

1. First make sure you are logged into your  Language Cloud as I am (top right)
2. Select Cloud-based resources from the dropdown



3. Make sure Machine Translation is listed as a resource 

B. With an App (Language Weaver Cloud)

Details found here: https://appstore.rws.com/language/app/language-weaver/941/

With that said, we are currently experiencing issues downloading apps so if NMT is what you are after then please review option A for now.

The last point I will raise is your 

Giulia Caldaronello said:

I cannot contact any of them to receive proper reply and support, even though I've paid and I still pay quite A LOT for their services!

I checked what I believe is your account and your SMA status is inactive. If you have paid for support then you could contact support direct.
If the inactive status is incorrect and there is an account error then let me know so I can get this addressed for you.

That said there is a team of us that manage the RWS Communities and our levels of support tends to result in proper replies and happy endings.

Lyds