It is also getting another error:
The information from this topic indicates that the Instance Service is using a local user instead of a Domain user. That is not accurate. However, it is using Network Service as the user, which seemed like it should have been correct. This is the case on both the Primary and Replica server. Please change this user to the\Administrator and the error will go away.
If you then got other errors please add Generate Audit rights to that user and also add it to the Domain Administrators Group, and restart the service. Please do it on the all servers you are using.