Thank you for your message.
To use the “Update List Item at Any Site” you need to first define a dictionary with the values you want to use to update the list item. You can learn more about working with dictionaries here.
Remember to use the internal name of each column and the correct data type also for this.
Then you can use the “Update List Item at Any Site” action along with the dictionary you’ve just created.
Please notice you’ll specify the item’s ID of the one you want to update. You can use a simple lookup to do it too.
You also have to specify the list name or URL but that’s quite simple.
And that’s basically it. If you need anything just let me know.