[Solved] unable to upgrade addons

I have several WPDiscuz add-ons installed on a multisite WP install where I have network activated the Divi Theme from Elegant Themes and a child theme of our own.

I use latest versions of WP (5.2) and Divi, and WPDiscuz seems to be in latest version (1.3.0) as no upgrade is proposed for this extension.

I have updates proposed for addons Comment Search (1.3.0 to 1.3.1), Emoticons (1.2.4 to 1.2.5), MediaUploader (1.3.8 to 1.8.9), Online Users (1.0.8 to 1.0.9).

When I connect to network admin and want to apply these updates, they all fail for the same reason:

Update Failed: Before you can receive product updates, you must first authenticate your Elegant Themes subscription. To do this, you need to enter both your Elegant Themes Username and your Elegant Themes API Key into the Updates Tab in your theme and plugin settings. To locate your API Key, log in to your Elegant Themes account and navigate to the Account > API Key page. Learn more here. If you still get this message, please make sure that your Username and API Key have been entered correctly

But I have entered Elegant Theme Username and API Key, and updates work well for Divi Theme and all other plugins I have on this multsite install.

I have also activated all the WPDiscuz addons for every site of this multisite install (this is a tedious process, I hope a future version will enable a network activate of addons in one click, but this is not the issue here.

Please advise on how to proceed to get these updates, and all future WPDiscuz add-ons updates, applied.