Question Cannot leave comments.

I don't know why you are not being redirected to the forum when you disable the Discuss login and click the button 'Posts in discussion'.
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I'm not sure how to do a redirect so that when someone wants to make a comment, they get a space to type their comment.

You can disable the redirect plugin again, you don't need it for this redirect.
It won't work the way you want it to, unless your Joomla articles are all in the same category.
You can only create a single redirection with the user login. This means that if you create a redirect to a category in which the article is located, you would have the comment field.

But the redirection will always go to this one category.
Example:
If you create a redirect to Joomla category 1, you will always be redirected to category 1, even if you click the login button for an article in category 2. So you have to go back to category 2 manually if you want to comment an article in category 2.

Possibilities to create a redirection:
Redirect to a menu item.
Click on ‘Select’, a window opens and select a menu item e.g. Home
Then you will always land on Home when you log in via Discuss (image 1) Or you create a Category list menu item and redirect the login via discuss to this menu item. But then you still have to navigate to the correct category first.
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Redirect to a category.
Enter the URL to the category which contain the articles (instead 8 your category ID). Then you will always end up in this one category (image 2).
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First make sure your Kunena menu works and delete those menu-items from your main menu
 
www.kunena.org/docs/en/troubleshooting/menu-issues
Then make a redirect to your forum by chosing your Kunena menu-item in the field Menu Item Login Redirect (your alias will be different from my screenshot)
 

 
 

I've patched the plugin so it stays on the article page after login. Install the attached plugin. (Version 2 because of minor flaws detected by @rich)

When I went to the GoDaddy server, I installed Kunena Fourm and Discuss, which worked immediately. No problems!

I'm not sure why the Cloud Access servers do not work immediately. Being a newbie, I prefer for things to work out of the box. So I'm debating on leaving Cloud Acess and going with GoDaddy. Thanks for trying to help, but it's just getting too complicated.

I'd rather think you made some mistakes. My testsite on cloudaccess is working flawless.
And for what it is worth, I've seen some bad user experiences with GoDaddy.

@OldCharlie Have you installed the Discuss plugin uploaded by @Pinkeltje? If you then again remove the User-Login menu item you created yourself, the login via Discuss should work the way you want it to.