No. Odoo apps page is not down. The problem is with your URL. I hope you are looking for the below modules.

Link 1: Document Management System

Link 2: Employee Documents

Hello, 

I am having similar issue with a few modules. Paid and free, not able to download gives a 500 error. Any thoughts?

Hi, 

The issue is not with all apps in the store, here for the modules that you have tried, the author might removed the code/module from their repository, even though the module is removed from repository, sometimes the modules will still show in the app store. That might be the issue here too. 

Either you can check with the author of the modules or you can connect with apps@odoo.com and see what they says. Meanwhile you can check the other alternative modules or check with the github repo of the author. 

Thanks

Update: Now it works. Apparently something was fixed on the server side.

Thanks. 

Those links lead to the very page I am referring to. The download links for Odoo 11 versions of the apps give 500 Error.