how to transfer icloud backup to new iphone

I bought a new (to me) iPhone 8

#1 I did a backup on my (now old) iPhone 6

#2 I started the migration by holding the old iPhone close to the new one and all was good until I got to the part where I was to login to my apple-id account

# now my iPhone is "spinning" while telling me: afventer godkendelse (awaiting authentication I believe is the english term)

So - I turned on my iPad and tried to login to my apple account - but now my iPad is spinning too :(

It's not the login - I tried to login via my husbands browser and that worked OK - so I guess it must be some dead-lock or what not?

any thoughts, help, would surely be most welcome :)

love,

Anne