ReflectionException] Class PayPal\Api\PayoutSenderBatchHeader does not exist
error while running
php bin/magento setup:di:compile command
It happens when some class of other modules has been used in third modules and that module are not present in magento.
In your case
PayPal\Api\PayoutSenderBatchHeader class is used in somewhere in other module expect PayPal module.
You need to remove the use of PayPal class from other modules or install module of PayPal which contain
PayPal\Api\PayoutSenderBatchHeader Class in its file structure.