CREATE LOGIN 
datarep_user WITH PASSWORD = '
password';
GO

use [master]
CREATE USER 
datarep_user FOR LOGIN 
datarep_user;
GRANT VIEW SERVER STATE TO 
datarep_user;
GRANT VIEW ANY DEFINITION TO 
datarep_user;
GRANT SELECT TO 
datarep_user;
GO

use [
source_mssql_database_name]
CREATE USER 
datarep_user FOR LOGIN 
datarep_user;
EXEC sp_addrolemember 'db_owner', '
datarep_user'
GO

To connect to Microsoft SQL Server sources from the Data Replication Console
To create backup logs for Microsoft SQL Server sources with the Server Manager
To enable Change Data Capture for a replication job

use [
source_mssql_database_name]
EXEC sp_addrolemember 'db_backupoperator', '
datarep_user'
GO

sp_configure 'remote admin connections', 1;
GO
RECONFIGURE;
GO

use [
source_mssql_database_name]
EXEC sp_addsrvrolemember @loginame= '
datarep_user', @rolename = 'sysadmin'
GO

If the user has the sysadmin role, the Extractor uses the DBCC LOGINFO command to get the information about the VLFs in the transaction log. This method is faster.
If the user does not have the sysadmin role, the Extractor scans transaction logs and processes VLF headers to get the information about the VLFs in the transaction log without running the DBCC LOGINFO command. This method is slower.

ALTER DATABASE 
source_mssql_database_name SET ALLOW_SNAPSHOT_ISOLATION ON;