I didn’t find how to create this action via button (next)…
For use Multiselect drop-down component you can have a many to many relationship and before you come to that screen you need to create the record and in that screen you can update it!
This video is about using Logged in user to filter the list.
You can create a many to many relationship on the collection that you are trying to create the record with the dropdown values and then before you come to this screen you can add a Create action on that collection and then you can add the link action to go to that screen and in that screen in the multiselect drop-down component you can add the Update current record and add current value of the multiselect drop-down to the that many to many relationship property!
Thanks for the info, I’ll try to do it.