Manuel Garcia

Thanks for the answer.

The OS is  Ubuntu 20.04.6 LTS. Supported.
The graphics card is an Nvidia RTX A4000 which is supported (However, The website says it hasn't been tested in Ubuntu)

This is what I have done so far.

Checked all dependency libraries and install the missing ones.
Check the Nvidia Drivers
Reinstalled Ansys.
changed the symbolic link of in the fluent folder to the installed by Ubuntu. 

Now fluent run if it is launch standalone  but 

 I still have the problems:
      Structural module: Mechanical aborted with a core dumped 
      Fluent: Fluent doesn't run properly from within Workbench. Produced the error reported in the original message