DefaultAppPool is not an account, it's an app pool. Inside that app pool you can define which account it runs under (advanced settings / Identity)
Assign it a windows account that has sufficient privileges. Normally you would create a windows account especially for the purpose.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…