Hitting PhantomBuster's API with a big list of profiles in the payload gets you {status:error, error:'Argument too big'} - the API does not accept large arrays as arguments. Point the Phantom at a Google Sheet or CSV instead and let it pull the input itself. If you are unsure of the argument shape, open the Phantom Setup, hit the three dots, and 'Switch to JSON' to see the exact format it expects.

Context: PhantomBuster support (answered on their LinkedIn Outreach page): launching a Phantom via API with a large list of profiles (~750) in the payload returns {"status":"error","error":"Argument too big"}. The cause: passing the profiles as an array in the API payload. The fix: use a Google Sheet or CSV as the Phantom's input instead of the array. To see the exact argument format the Phantom expects, open the Phantom's Setup, click the three dots in the top right, then 'Switch to JSON'.