Problems with Google Backup and Sync

I back everything to OneDrive but also wanted to back my pictures up to Google Photos.  I was using Google Photo back up to move the photos I moved from my camera to Google Photos but noticed some were missing.  I also found out that Google changed to Google Backup and Sync now and was afraid I’d end up with a lot of duplicate photos if I back up the same folder again even though some were missing. 

The biggest problem I ran into is that when I sign into Google Backup and Sync, I get a page not found error and get stuck.  Anyone else have problem with this or no what might be causing it? As long as the pictures have the same name do I need to worry about getting duplicates being uploaded and displayed?