I can't seem to install an app of marketplace

You could try with the web site: https://marketplace.firefox.com/#! Marketplace app may have an issue, waiting a fix.

I tried that but it said (APP NAME) download stopped.

Does it still happen after reset device? (Settings > decvice info > reset, that will erase your data)

I tried it but it does not work (tried it in the past and got the same result)

Does it happened on several apps or just one in particular?

It just happens on one particular app

its called sparksview RDP

It just happens on one particular app

its called sparksview RDP

So it's not a problem from the Marketplace, but from this app. Contact the developer, he may not be aware of it.

OK I just emailed the developer and I think he is going to sort it out.

I tried to install this too and I have the same result than you

Yeah it does it everytime I do it I thought it was a one off but it was not and I want this app if this is a packaged app the developer could send the zip file and install it using the app maker mozzila has.