Hi VoidTheFox,
Welcome to the Apple Community, where some of us do our best to help each other :)
Apple ID is the Account you use for everything Apple, including the App Store, iTunes, Music, iCloud, subscriptions etc,
If you want to login to your Apple ID account, you can check your payment methods are in order there.
(Eg: It may be that the main card you use for payments needs the expiry date updated ?)
Apple ID Log-in:
https://appleid.apple.com/
Articles online from Apple Support that may help you:
Change, Add or Remove Apple ID Payment methods
https://support.apple.com/en-us/HT201266
If you have recently changed your Apple ID or Apple ID password, you might need to follow the steps in this article:
What to do after you change your Apple ID or password:
https://support.apple.com/en-au/HT204071
If you need more:
Apple ID Support Page:
https://support.apple.com/en-au/apple-id
How to Redownload apps, music, movies, TV shows and books
Get help if you've removed content from your device or you want to download content onto a new device:
https://support.apple.com/en-au/HT201272
Hope this helps you get everything you do at the App Store working smoothly :)