Is the tablet in tablet mode? Without tablet mode enabled the keyboard won’t pop up when necessary.
Bottom right notification icon and there should be a ‘Tablet mode’ option. Tablets should default to it enabled, but sometimes don’t.
Tablet mode will give you full screen start menu though and apps run full screen. It makes way more sense though when used as a tablet.
Some traditional desktop apps (as opposed to tablet style “metro” apps – those you get in the Store) don’t always trigger the keyboard, so you have to use the keyboard icon in the bottom right. That should appear by default if Windows detects the device as a tablet.
Other thing is make sure you’ve got all the updates. If it’s new then possibly it won’t be shipped with the latest. There will be numerous updates and then after a while it will eventually pull down the Anniversary Update which is a major update.