Can you tell me how it works? When you enable this plugin, a link to the file appears on the ad page. But the file is available for download even without payment. The Osclass Pay plugin is enabled.

You need to link these 2 plugins.

You need to link these 2 plugins.

What does it mean to bind? Where will the file be available for download after payment?

In user profile and on item page

In user profile and on item page

I linked everything, but in the end the funds for the purchase are debited, but there is no download file in the downloads after the purchase. In the admin, in turn, the file also has the name of the file, but it cannot be opened, and when you hover the mouse over the inscription: "File removed"

File must exists first.
When you have download link on item page, it will be enabled.

If you enable it on the ad page, it is always available for download. And it is necessary that it appears in downloads in your personal account and only after payment. But after the payment, he does not appear there!

Then its not connected to Osclass Pay Plugin or listing/item has 0 price.