Do you have to have activated your Windows account to install Minecraft Windows 10 Edition on your PC?
No.
As long as you have bought the game and are logged in, you can install it.
If I select the trial version and hit "Install on device" and select my device it doesn't work. What could that be?
Is there a mistake?
No. Absolutely nothing happens. It says that it will be installed and then 20 minutes later there's still nothing.