(See
https://boardgamearena.com/reviewer)
You need all of the following:
- You must have played more than 50 different games.
- You must have played more than 750 games in total.
- You must have a seniority of at least 5 months on Board Game Arena.
- You must speak English and have indicated it in your language preferences.
- Your reputation on BGA must be absolutely perfect.
Since you're quite far from that, you need to fall back to the alternative of being an alpha-tester for a specific game rather than a BGA reviewer. For that you need to be added by the dev of the game itself. Some devs will post on the forum when they are missing out some testers (I remember seeing message from the Dice Forge dev when he needed alpha-testers for the expansion).