yes, if you wish to use the Gutenberg Editor, please see this thread for if and how to do this:
https://wordpress.org/support/topic/how-to-enable-gutenberg-blocks/
So do I need to install more plugins? bbpress, blocks everywhere, gutenberg?
yes you need to follow the instructions
I tried, I installed bbPress, Block everywhere and Gutenberg 20.6.0 but it doesn’t work. If I don’t install Gutenberg plugin I get critical error on the site. If I install 20.6.0 then I don’t see reply window and see js errors:
Store "core/interface" is already registered.
Uncaught Error: You tried to opt-in to unstable APIs without confirming you know the consequences. This feature is only for JavaScript modules shipped with WordPress core. Please do not use it in plugins and themes as the unstable APIs will removed without a warning. If you ignore this error and depend on unstable features, your product will inevitably break on the next WordPress release.
at t (implementation.ts:101:9)
at 772 (index.min.js?ver=1.0.0:13:2251)
at o (index.min.js?ver=1.0.0:34:44729)
at index.min.js?ver=1.0.0:34:45918
at o.O (index.min.js?ver=1.0.0:34:44999)
at index.min.js?ver=1.0.0:34:45931
at index.min.js?ver=1.0.0:34:45937

ok, I am just a guy trying to help, I do not work for bbpress, and I simply listed what I did on my test site to get it to work.
so I cannot help for your specific site, but you have installed guttenburg 20.x when the instructions say a different version.
But if the instruction don’t work, then you are on your own to get it going.
I rolled back gutenberg plugin to 17.9 (regarding blocks everywhere github repository) and it’s the same. I think it doesn’t work anymore. WordPress uses new API in core and need to add support new version of WP and Gutenberg.
I’m not quite sure what point you are making.
bbPress does not support blocks, it may do at some future stage, but it does not do this now.
Wordpress support uses bbPress and has a fix they have decided to do in order to support blocks.
I did some experiments to see if I could get blocks working with bbpress.
I said in the other thread that I could not get blocks working with 19.7, so it is probably not surprising that you couldn’t either – I’m not sure why you thought this would work. I did get it to work with 16.7, but I have not tried it since 6.8 was released (nor do I plan to).
It is up to plugin authors to decide what they wish to support within their plugins, and whilst you think it would be good to be able to use blocks, this is entirely up to the authors of free software.
Whilst personally I would not wish to impose blocks on my forum users, as I find it unintuitive, I would support adding the capability for those that do want it.
For the time being, unless you can get it to work, then you have the editor as per this forum, or the visual editor which can be added using the bbp-style-pack plugin.