Interesting. I ended up trying it out with the newest version of WordPress. It does have issues with the newest version. It has about 3 widgets. 2 of them didn't work and I got the last one working. 
So far from what I understand is every user visiting your WordPress site needs the alby browser extension which I downloaded but since I don't have an ably account I could send any Satoshi to see if it worked. I think it would of worked. 

I was hoping I could use my BTCPay sever to generate the invoice and bypass the browser extension as not everyone had the alby extension. If you use BTCPay server the user just goes to the link and he can pay through there. 

I also don't think when users pay it shows the donation amount & comments. It would be cool if it left the comments and amount for everyone to see. 

I do see some BTCPay sever setting in there. I will keep paying around with it. Alby seems be doing a lot online for Bitcoin. 

I'll keep an eye on the development of it. 
For now that plugin gave me an idea. I will just post a link to my BTCPay server store and they can donate through there.  

 The Plugin can easily connect to a BTCPay server or any NWC enabled wallet. 

The plugin focuses on inline donation and paywalls/buttons. It should make it a one-click experience for the visitors because the mental transaction costs are the biggest barrier, so we need to reduce those as much as possible.

With the Lightning Browser Extension it's literally just a click, if users don't have the extension it works fine and people will just see a QR code to scan. 

Let me know where you had issues we're happy to help.