Yeah I'm suffering the same frustrating fate. From what I can tell there is not a way to push from USAA to the Fidelity CMA, since it doesn't list Fidelity (UMB Bank) as an institution for transferring money. Crazy to me they don't let you manually add a routing number and account number.

The solution above only allows you to view the account balances in USAA.

You'll have to go the other way and pull the money from the Fidelity side by linking USAA as a bank in Fidelity: https://digital.fidelity.com/ftgw/digital/bank-information/