Pro version not working

Hi,
We’ve tried in every way to update the plugin to the Pro version, but on the Account page of the plugin we haven’t found any download button. We also tried to downgrade WordPress to the version tested with the plugin, but it doesn’t change anything.
How can we solve this problem?
Do we have to install the plugin again and give the license code?
We paid for the plugin for the pro version but despite this nothing changes, we cannot access the paid features.

Thanks.