Not able to access the app on iPhone

Hi ..
I have purchased the annual subscription of Adobe Reader in Nov 22. Everytime I try to access the app for editing or creating a document, I get this msg to have a subscription . When I click on subscribe now, I get this msg n after clicking on OK it keeps buffering. Donno Wats the issue but Wats d point on have such an expensive app wen I can use it.
kindly resolve it else process refund. Looking for an immediate response.
regards
