I found https://learn.microsoft.com/en-us/azure/azure-sql/database/replication-to-sql-database?view=azuresql and it says:
Publishing to any Azure SQL Database from a SQL Server database is supported by the following versions of SQL Server: SQL Server 2016 and greater SQL Server 2014 RTM CU10 (12.0.4427.24) or SP1 CU3 (12.0.2556.4) SQL Server 2012 SP2 CU8 (11.0.5634.1) or SP3 (11.0.6020.0)
And you are SQL 2008 R2. Time to upgrade, I guess!