Board Game Arena

Going through tutorial I'm supposed to click 2 Galatic Trend Setters cards to pay for Space Marines card but only seems to be able to select 1 card. I select 1, it goes green, I select the other, it goes green but unselects the first. Not sure if this is a bug in the tutorail or user error but have tried multiple ways to select both cards but no apparent way to do so. Can't report as bug because there is no table # on tutorials.

directly message to the tutorial's creator?

Hum, maybe you are selecting them to play ?
You have to select the spaces marine to play and then you'll be asked to select cards to pay.

But if space marines is the only card you play this turn, then the final cost is 1, not 2 and you only need to select one card for payment.