Cancel subscription

I have an iTunes subscription for the AllTrails Pro app service, which I am trying to move over to Google Play, as I no longer use an iPhone. I had set the subscription up on an iPhone 6 which stopped working. I have an old iPhone 4 which I used to sign in and try to manage the subscription, but when I click on 'Subscriptions' in my iTunes account settings all I get is a white screen (nothing shown). I signed out of my Apple account, restarted the device, and signed back in which no success. I then signed into iTunes on my PC and can see 1 subscription listed in my account settings, but when I click the 'Manage' link nothing happens. Some of the other links on that page work, but not that link to manage subscriptions. I'm debating just blocking access to my Paypal account if I can't get the subscription cancelled otherwise, but I'm not sure if that will cause an issue with AllTrails when I try to add the subscription through Google Play. Is there a customer support staff member who could help me with this? Thank you.