You need not do anything. If you check your government icon on the left side, you will see there is a 4% chance one can show up on your build tab each cycle.

Adding onto that, you only unlock the ability to roll Maelstroms after you complete the research option to unlock Venators. This will also lower your chance of rolling Praetors and Procurators.

alr thanks

is there a way to edit the files and allow the republic to outright build ships that can normally only build through the market?