If you are not getting the Twitch verification code while activating it on any of the devices, check your Internet connection. Make sure that your bandwidth is high, if it's not, then try contacting your ISP and consult him. You should also check Twitch's server and make sure that it's not down. However, if you are not getting a verification code while creating an account, then you should check your Spam and Promotion folders, sometimes, these emails get misidentified.