What should I do? 

Your best bet would be to get an iPad and install H9 Control on it from the app store.  Some users have tried to run H9 Control on Windows tablets, but I wouldn't recommend trying that.  Some Windows tablets have arm chips which won't work.  Some have Intel chips which will work.  Of the Intel based Windows tablets I think people have been able to use H9 Control on the Surface Pro without any significant problems, but Eventide hasn't tested H9 Control on the Surface Pro so we don't claim that it's error free or recommend getting one.