You can shorten the chain yourself.
Where did you buy your kit from?
Is it 415 engine chain?
Go to a bicycle store or Ace hardware and buy a chain breaker but make sure it works with your chain that is probably wider than bicycle chain.
If you have a grinder you can grind the pin off and punch the pin through with a nail punch or even a nail to shorten your chain.
Put the link over the open end of a socket when you drive it through the chain side plate.