Hello and welcome @Brian_P_1 
Unfortunately, I donāt believe quarterly is an available option at the moment. Though it has also been mentioned recently in this topic Stripe Payment Gateway feature request - #24 by Chaitanya_Khanna, so may be worth a dedicated Contribute > Feature request. 
I think the Subscription flow is to have people signup for the āfreely availableā section of your site, and then subscribe to gain access to the gated areas. There may be other ways to achieve what youāre looking for though, but Iām afraid I donāt have experience of those. If nothing is popping out using the Search you may get more knowledgable replies from a fresh Support topic. 