I'll share information where you can get the SBA PPP Loan, so you're able to enter it in the application form.
You can find the loan number on the treasury documents you've received when your loan is approved. The papers contain the complete details that you need in your second application.
If you have difficulties finding it, you have an option to communicate with the PPP supports. They have tools to check and present you with the SBA loan number. To reach them, go to the PPP Center area and hit Live chat.
I'd also share this information with you about the qualification for a second loan in PPP loan for your reference.
I've added these pages below about handling the various documents, funds outlined by the SBA, and other relevant topics.