iAqualink for Pool Equipment strike again

hi Paul , thks ,
I've already gone through this doc, but to be honest I'm not into it enough to understand, I started with a few examples, like spotify , which I can't reproduce.
I get a nice token that I put in a flow.
image

it doesn't work anymore is when I try to reproduce this:
'{
"Authorization": "Bearer " & $flowContext('spotify').tokens.access_token
}'
how to replace <<& $flowContext('spotify').tokens.access_token>> by
image
that haven't no "copy path" by the way. (? Copy path of a variable from Debug Node does not work)
thks again