I had a had the same error message at first. It seems that trying to assign a name for a new routine in the Alexa app first was confusing something.
I did the first setup in the flic app, then changed over to Alexa. Enable the skill (if not already) then create a routine. Instead of giving it a name, try going to the 2nd option “when this happens”, choose “smart home” then your flic button. It then gives it a name, and let me pick the actions to perform.