It's a little buggy so it might not place towers even with the correct amount of money to place them. If you have enough money, place a tower. There are 3 towers, Basic ($300), Red Pink ($400), and Crossbow ($650). The basic takes 1 damage, Red Pink takes 3 damage, and Crossbow takes 5 damage.
Credits to @Shed4rd (or Daniel Smith, as his YT channel's (and maybe even his real) name goes by) for the tutorial.
