This is a simple two-step process that usually all authors including me follow for CVPR submission.
Step 1: Keep paper ID blank in your word/latex template and submit the paper as it is. Now your submission will be assigned a number.
Step 2: You can edit your submission till the cut off timings. You need to update the paper ID which you received in step 1 .
Now your submission will be with paper ID in manuscript.
I hope this is clear now.