(NOTE: This solution is copied from my solution on TA)This achievement is earned by completing the faction questline for the Freestar Collective.
The questline starts in Akila City where you are asked to resolve a hostage situation at a bank. Once you resolve the situation, you will be asked by the Marshall to speak to an Emma Wilcox who will ask you to complete a mission on the Mission Board, after which you will become a deputy and the questline begins in earnest.
The questline consists of the following quests:
- Job Gone Wrong
- Deputized (you earn an achievement here)
- Where Hope is Built
- Shadows in Neon
- Surgical Strike (you earn an achievement here)
- On the Run
- First to Fight, First to Die
- The Hammer Falls (this achievement)
As far as the "role playing" aspect goes, you are expected to uphold the law above all else, while also protecting citizens. You will also be given guidance along the way from some of the NPCs on how to handle some of the situations. Also as part of this, you will have to run the Red Mile (I was not able to find a way to not have to do this, but it was easier than I expected).
Once the questline is completed, the achievement will pop. Speak to the Marshall again, and you will receive the Star Eagle ship as a reward. It does not require a registration fee.
NOTE: An Xbox/Game Pass owner stated there can be a problem with talking to Mei to initiate the Red Mile run in the On the Run quest. It might be a good idea to make a manual save before talking to her just in case. Then, talk to her, but back out with the "I want to prepare" option and then start the conversation again and try to start the Red Mile. If that doesn't work, reload your manual save and try again.