To link a Savings account to your 360 Checking/Total Control Checking for Free Savings Transfer, the Savings account ownership must match your 360 Checking/Total Control Checking account ownership in order to be eligible.
If there is a Savings account you want to use but you don't see it as an option, check to see if it's with a joint account. If so, make sure your account ownership matches your Checking account. For example, if you are the Primary Holder on a joint Checking, you must also be the Primary Holder on a joint Savings for it to be eligible to be linked for Free Savings Transfer.
You can not link to external accounts (at another bank).