loading information from my current phone to a new phone

I currently have a company provided Iphone 7 running IOS 12.3.1 and I wanted to get a separate personal phone and wanted to save all my contacts and pics and such to the new phone. I got another Iphone 7 as this is just to be a backup phone for now (at least until I leave the company when I retire or something). I backed up my current phone to the Icloud account as instructed by the people at the AT&T store and then I tried to import that to my new phone, however, when I do that it does not work. The backup shows up in the options to load (its the only option) but when I select it and enter the password, it starts calculating a Time remaining and then after 30 seconds or so it comes up with a message that says "cannot restore Backup". The guy at the AT&T store indicated that I had to get help from Apple to fix this problem.

Any direction on what to do to resolve this?