I logged in to the support forum. Your link is still unusable, however I did a search in the forum using part of your link’s text and found:
https://kriesi.at/support/topic/problems-to-update-to-enfold-4-5/
which has a runup of the manual update procedure. Nothing special, but good to have a confirmation that replacing the enfold folder is actually all what you need to do.
Case is closed for me now.
Thank you for your prompt replies (but you need to review that link of yours ;-)

Kind regards, Paolo