El lenguaje de ese forum es inglese. Por preguntas en español, usa ese URL, por favor: https://learn.microsoft.com/es-es/answers/questions/. Non hablo español sufficiente bueno per escribir un respuesta en español, más responde en inglese.
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The language of this forum is English. For questions in Spanish, use https://learn.microsoft.com/es-es/answers/questions/. I don't speak Spanish well enough to write an answer in Spanish, so I respond in English.
First of all, SQL Server Management Studio is not giving you an error. SSMS is just a tool you use to communicate with your data source, and SSMS relays the error message from the data source.
The SQL code you have posted is legal syntax in SQL Server on-prem, and also in Azure SQL Database.
However, the style of the error message, tells me that you are using Azure Synapse Analytics which is a different product. Synapse also supports T-SQL, the same SQL dialect used in on-prem SQL Server. However, Synapse has a completely different background, and far from all syntax supported by SQL Server is supported in Synapse (at the same time Synapse has syntax not available in SQL Server).
The error message makes it clear that table variables are not supported in Synapse (which makes sense since that Synpase is a multi-node database).