I’m trying to move my photos for sale from Fotolia to Adobe Stock

As of my information there is one operation that needs to be done and you are on Adobe stock. Your existing picture are effectively since a long time on Adobe stock. 

Look here for relevant information: https://www.fotolia.com

I think that Fotolia support is still available, supporting you in your transition. Try it out.

Report back if after having read the info, you still need help.