Are you sure you got correct brushes for Sai? because these are brushes for Photoshop and it's stated so in description
Sai brushes are these Paint Tool Sai - Dragon Scales Pack. Sai installation folder is typically C:\Program Files x86\Paint Tool Sai or C:\Program Files\Paint Tool Sai You can use windows search function to search your hard drives for sai.exe location.
That looks so freaking amazing! But sadly I don't have paypal and no money to buy brushes or to buy points for here to use on the brushes. Oh well, still faving it because looks cool but there went my hope that was high thinking be free only to see it wasn't so that high hope came down fast with a crash. >_< -goes back to listening to music-