PayPal payment features were removed from Koha in 21.05 - see Bug 23215 - Remove PayPal logic from Koha, in favour of using plugins for payment processing. Remove the payments section from OPAC system preferences: - EnablePayPalOpacPayments - PayPalChargeDescription - PayPalPwd - PayPalReturnURL - PayPalSandboxMode - PayPalSignature - PayPalUser