3 published complaints: 1 resolved for the player, 2 unresolved (2 no response).
Sweepolis is an established Delaware operator with published sweepstakes rules and a well-regarded sibling brand, and it grades C on SweepsGuard. It has paid a disputed amount in full within a day when a player pursued it directly, and it has reinstated a closed account after a player raised the issue publicly. The concern on record is reachability rather than outright refusal to pay.
Sometimes, and the route matters more than usual here. Of the 3 complaints on record, one ended with Sweepolis paying in full within a day of being contacted. The rest closed unresolved after the operator did not respond within the five business days SweepsGuard allows.
Be aware that the support address Sweepolis publishes rejects mail from third parties outright, so anyone escalating on your behalf will be blocked before the message is read. Their Zendesk support channel does accept mail and issues a ticket reference. Players who have pushed directly, and publicly, have had the best results with this operator.