Report can't open in the web portal, just downloaded in the navigator

Hi,

 I worked before with power bi services (cloud). For internal needs, I have to go with on promises choice. I'm new with Power BI Report Server on promises. I prepared the environment properly (installation & configuration) with the last version. The web portal work to me, but the problem focus in 2 points:

• When I upload a report power Bi which I had created before with the normal power bi Desktop, the upload succeeded but I can't open it. When I click in the file in order to open it in the web portal, it is being downloaded in the navigator( Firefox). I tried many times and I have the same reaction. I'm in urgent situation, I have to find solution
• The first time I tried to open my report (created before with normal power bi desktop), the power bi desktop RS show me message impossible to open  the document;The queries were created with a more recent version of Power BI Desktop and may not work with your version. Please install the latest version to avoid errors during the refresh process. But if I close the message, the document opened. I tried also to save the file as report server placement, I failed with my link(I'l sure it's right) but I got a message that our server inexistant with that address.