I tried everything step by step. At the end in step two it ask me how I would like to connect to my wallet, I select metamask. Then I click generate transaction and it gives me a raw transaction and signed transaction. The signed transaction automatically gets pasted into the sign transaction box in next step 3 which is the last step. I click send transaction then it give me a red signal at the bottom which says error_13 invalid signed transaction.
Here are options to try:
1) connect with a different browser entirely (eg Chrome)
2) Use another method apart from Metamask to unlock your wallet.
If you're going to enter your private key or seed into any website, download the MyEtherWallet website
from here And and do everything from there, then copy the final signed transaction and paste it in the online website to broadcast it.