I am asked to follow Ciri, but she does not move? what can I do?

Such issues are usually caused by corrupt and/or damaged game files. In some cases it can also be caused by badly programmed or obsolete mods. Start by deleting all mods. Then do the following:

If you are playing on GOG Galaxy go to: More --> Manage installation --> Verify / Repair.

If you have downloaded the game manually you will need to download it again and reinstall (you can save your saved games).

This should fix your issue.