Finder is asking to set up iPhone from new or backup

I just upgraded to Catalina and I'm trying to sync or add music to my iPhone 12. I have had this phone for several months. Finder will not proceed unless I set this phone up as new or backup from an old back up from 2017. How can I sync or drag music to my phone without wiping it or deleting any data? Will setting it as new erase any data? Thanks for any help.