Do you have a Fotolia account?
Are you trying to log into Fotolia account, or Adobe account?
If you had/have a Fotolia account, did you synchronize with an Adobe account?
If you did synchronize, are you logged in to one account while trying to access the other?
Is your experience as at Fotolia and Adobe Stock synchronization issue. ?
If the link does not help, pleas give us more details to work with.
You are trying to sync with a Fotolia account that has already been synced. You need to log in using the Adobe ID you originally synced with.