You'll need to check out with Visa Checkout for the coupon to work.
GMG is offering refund if the game is still not running smoothly for you after the first patch's release. More details here.
GMG has suspended sales but was $24 after coupon: DEALZO-N40OFF-BATAKV
Honestly if you're going to buy the Season Pass, we recommend just getting the Premium Edition for better bang for your buck ($54 vs $60 separately).