In reply to Tim Bedsted.

Hi Tim,
Thanks for reaching out. To create a variable using Powershell, you can use the following syntax $env:TOKEN = "ABCD-123". Here's a link to more info on variables and Powershell.
Specifically for this instance, it may be easier to run the curl command without the variable assignment, copy the access token that is returned, then use the code above and assign the value.