Yes. Just like playing magic in real life, you have to buy the cards.
Also, the account costs 10$ iirc but they give you like 2 event tickets (which are used as currency, so thats pretty much like getting 2$ right back) and a pack which is like 3 or 4$. So the start up cost isnt that steep. I would suggest you learn how to play magic in real life though before you try to play it/invest money into it online.
alright hippy i will kill you and wear your skin