Using List.Generate for Token-Based API Call

Your syntax doesn't look right to me.

Compare to the examples in this highly-related article:
How to use List.Generate to make API Calls in Power Query M

Code snippet from the article:

List.Generate( 
  ()  =>  [ Offset = 100, Pokemon = GetPokemon(0) ], 
  each [Offset] <= 200,  
  each [ Pokemon = GetPokemon( [Offset] ), Offset = [Offset] + 100 ],  
  each [Pokemon] 
)

Your code should probably look more like this:

List.Generate( 
  ()  =>  [ token = "", results = Output("") ], 
  each [results][EarliestEntryDate] > Date.FromText("6/15/2025"),
  each [ token = [results][continuationToken], results = Output(token) ],  
  each [results]
)