If grbgetkey produces a message that looks like this:
info : grbgetkey grbgetkey version 11.0.0, build v11.0.0rc2 info : Contacting Gurobi license server... error : ERROR 405: Cannot reinstall license 999999; get a new license from the Gurobi website
This means you are trying to set up an Individual Named-User Academic license on a computer different from the one for which it was generated.
To resolve the issue, simply request a new academic license. Connect your computer to the university network, then follow the instructions for Retrieving a Free Individual Named-User Academic License.