When wanting to use the Shiptheory integration to Royal Mail, you'll need to ensure that you have an active Royal Mail account. This is separate from PPI, Click and Drop and the standard Royal Mail account, and having any of these doesn't mean necessarily that you'll have an OBA account.
An OBA account has some unique features, such as scheduled collections and personalised pricing with Royal Mail, and it's also the account that allows you to receive tracking numbers through Shiptheory.
If you're unsure of whether you have one or not, it's recommended to verify this with your Royal Mail account manager and to check whether you have the following OBA details;
-Live OBA Email
-Posting Location Number
As long as your account manager is able to verify this, then there should be no problem getting your Royal Mail set up through Shiptheory. You can see the guide to that setup here.