On the app, I don't remember ever having to type anything, only tapping exercises in Korean. I might be mistaken.
On the computer, I don't think there is a build-in keyboard. You'll have to activate it on your computer.
For mac, it is pretty easy, just go into the keyboard tab of the Preferences. The better keyboard is probably 2-set as it is the most commonly used (also as actual physical Korean keyboards). It takes some time to get used to, but it is worth the effort.
For Windows, I'll let someone else shine in. Maybe an actual download is necessary, I don't know.
Lengthy process and as a long time apple-user I'm not so awesome at the windows, but here goes:
Open control panel click on 'search control panel' type in: input click on Change Keyboards or Other Input Methods the region and language window will open on the keyboards and languages tab click 'change keyboards' click "add" scroll down to "Korean" and expand the options (usually you click on the plus sign) then under keyboard, check the "Microsoft IME" then click okay. (I don't think you need the Korean keyboard checked because Microsoft IME is what lets you switch between English and Korean on a single keyboard) You SHOULD see the letters EN in the bottom right of your screen on the panel or you'll see a floating language bar (did I mention I'm not using windows 10? That's probably important). From there you can switch to from English to Korean. You'll notice that you aren't typing in Hangeul yet. you can click on the Han/Eng button and the letter A will turn into 가. You can now type in Korean (might wanna buy some stickers for your keyboard until you can memorize the layout). Fun note: pressing the left alt and shift will change your keyboard and once your keyboard is set to Korean, you can simply tap the right alt button alone and it will change from English to Korean. breathes okay that's all I got! Hope it helps!