you dont
...now, on a more serious note:
CGAs are by and large former NCV Testers. Openings for the NCV Tester role have only happened a few times throughout the last 5 years, based on how active the CGA team is at that time, since NCV Testers also have voting powers.
There is no such thing as "fail" or "pass" here, it's not an exam for the CGA role (despite the last application did look like an exam lol, it was clearly said in the announcement that we don't expect anyone to give 100% correct and exact answers), any NCV Tester application is just a way to let us know we can consider you as a potential candidate. Then it's up to CGA Team to decide whether to actually consider or not, based on multiple criteria and further discussion.
How do I become a cga?