Log in to your Apple Developer account with your main Apple ID, not the new one that you just created, and follow the steps below.
1. Click on Certificates.
2. Click the ‘+’ icon to create a new development certificate.
3. Select iOS App development & press Continue.
4. Download the CSR file provided here onto your desktop (CSR file)
Select the file after download and press continue.
5. A Download link now appears on the screen. Download the certificate & store it in a folder that you will remember.
6. Navigate back to your MyStudio White Label Control Panel > Apple > Developer information > STEP 5 Create a development certificate, upload the file you just downloaded here.