It is really simple to activate USA Network on Roku, you just need to go along with the steps given below:
Press Home button on Roku TV remote.
Launch the Roku Channel Store.
Search for USA Network and Add Channel.
Open USA Network and copy the activation code.
Go to usanetwork/activatenbcu on a browser.
Enter the USA Network activation code.
Choose your TV provider.
Now, you just Log In using the credentials with a TV provider and you will be able to watch all exclusive shows of USA Network on Roku.