Bulk transfer of files DropBox to iCloud/iCloud Drive

I want to transfer 99% of my files from DropBox to either iCloud or iCloud Drive and need some help to do that.

The only files I cannot put in iCloud are from Scrivener who advises against. I've used DropBox for years but am paying for 2TB when I only use 10 Gigs and I have heaps of spare free space on iCloud.

I also need to understand where I should transfer my files to, iCloud or iCloud Drive or doesn't that matter?

I hope someone can give me step by step for this. I did see an old post but DropBox didn't show up in iCloud so I couldn't follow that - and it was quite old advice anyway.

One further question: I remember not transferring files years ago to iCloud because I use Microsoft Office, not the Mac suite...am I right in reading that iCloud/iCloud Drive will now accept all Microsoft files.

Thanks in anticipation.