DOWNLOAD button not active for articles download

Describe the issue or problem
I am using OJS 3.2.1, and when I publish an issue, the DOWNLOAD button is not active for people to download the articles. I want the DOWNLOAD Button activate for users to download the papers.

What application are you using?
I am using OJS 3.2.1

Additional information
Below is screen shot of the button I am talking about

I think it has to do with the custom theme you are using. You can enable the default theme and check again.
If it works, contact the theme developer.

Ok, thank you, I will do that.