After opening the new SeamPay app, click on the 'Hub' tab and then the 'Donations' button. In the Donations screen, you can click on the option at the top for “Manage fundraisers”.
Select the fundraiser to withdraw from
Tap on 'Withdraw' to transfer all available money to your SeamPay balance
There isn’t a fee to create a fundraiser, but SeamPay charges transaction fees on the transactions you’ll receive for the fundraiser.