Follow the below steps:
1. Install R studio from here, https://www.rstudio.com/products/rstudio/download/
2. Click next to all and Click install.
3. Run R Studio.
4. Now type command and run.
5. Type below command and run
6. Type below function and run.
7. Now Go to Tableau and Open Manage External Service Connection.
8. A window opens, Select Rserve and default port is set as 6311.
9. To check connection, Click on test connection and click ok.
10. Now tableau can use R to perform operations.
Hope it helps!