I bought a new streaming stick, got everything set up and went to add Sling. It asked me for a PIN. I went into my account to see about adding the new stream stick and i did not see a way to do that. I deactivated the one account and started a new one but it's not asking me for info for my new stick even tho I have it marked for no pin needed it's still asking me for a pin?
The only way to add a Roku device to a Roku account is to factory reset the Roku device. If the email address that's displayed under Settings->System->About on the Roku device doesn't match the email address that you're using to log in at https://my.roku.com then you'll have to factory reset the Roku device to link it to that Roku account.
As for the PIN number, if it is Roku asking for the PIN you can log into your account at https://my.roku.com you can create or reset a PIN value. You can then choose when the PIN is to be required, such as before it will allow any subscription or purchase to be made on your account.
I don't use Sling but I've read Sling has its own PIN capabilities. Try logging into your account there and see what you can find re their PIN.