REST API Authentication

I am attempting to test some integration with NetSuite using the REST API. I have Postman set up with the sample project provided. I've added the Integration record to my NetSuite environment set to use TBA. I don't want to use OATH2.0 because in this situation I cannot make one call to get a token and then make a second call. It all has to be done in a single REST request. I've also set up the access token. So I have the Client ID/Client Secret and the Token ID/Token Secret.

I've put these into Postman along with my account id (a sandbox account). When I test, I get the below error. I saw one post that said if its a sandbox, then the account id should be in the format of: XXXXXX_sb1 using an underscore and not a dash like what shows in the URL. But when I use that, I get another error saying that the account is incorrect. I've also checked the audit log inside NetSuite, but there is no entry for this login attempt.