Setup a SynapsePay account but cannot deposit USD into Kraken due to Insufficient Documentation with no other directions. This doesn't seem like ACH linkage between US banking accounts.
You're right, it's not an ACH linkage. It's a wire deposit. First you have to activate your Synapse account with Kraken (Go to Funding > Deposit > USD > SynapsePay in your Kraken account and follow the instructions). After the account is activated (this can take up to 3 working days I believe), you then go again to Funding > Deposit > USD > SynapsePay in your Kraken account. There you choose an account (one of the bank accounts you've set up with Kraken to use for SynapsePay) and the amount you want to deposit. Then you click "Review Deposit" and "Confirm Deposit." You will then be taken to a screen that shows you the wire details you need to use to send the wire. The details include a reference number that you must include in the wire. Also, you must send the amount that you indicated. If you tell us in the form that you are going to send $5,000 but then send us a wire for $4,500 this will definitely delay things.
I hope this helps clear things up. If not, contact us through support or feel free to DM me with questions. I agree that the documentation is insufficient, so I'll look at getting some better documentation up in our support center.