Making a new submission to arXiv
If you are an Overleaf user, the easiest way to prepare a submission is to use the “Submit” button on Overleaf and scroll down to arXiv, download a zip file with all the needed files for your paper, and then click on the Submit button that takes you directly to arXiv pages for a new submission. See here for Overleaf’s detailed instruction page.
Alternatively, Overleaf provides you a zip file for streamlining your arXiv submission by providing this .zip file available for download. You can simply download the .zip file and it will have all the files needed, including the .bbl file for the references.
Updating an existing submission to arXiv
When revising a submission, Overleaf does not offer a “resubmit” button. You will need to download a zip file and replace the files on arXiv that have changed. If you’ve never done this before, follow the guidance here.