Gacha is the primary way of obtaining member cards. Each gacha pull costs 300 quartz, where if you do a 10-pull, you are guaranteed a 3★ or better member card. A single pull can be done once a day for 100 paid quartz. Go here to see the current and past gacha banners.
Any given gacha pull has the following rates:
In case a 10-pull is done, then the 10th pull will have the following rates: