We do not provide support for localhost environments. I do not know why your localhost install does not work. It's either a server configuration problem or even possibly a permissions issue on your computer itself. I do not recommend using XAMPP for localhost either. I suggest using Laragon, at worst WampServer, and at best using Docker.

Again, I can not help you with localhost issues. It is an unrealistic environment to debug. If you experience this on a live site then I can debug this further. Any number of issues could be caused entirely by your computer. CB Auto Actions works perfectly fine in all my localhost environments. Try deleting the below directory to delete CB Auto Actions in the file system only then try reinstalling it.

/components/com_comprofiler/plugin/user/plug_cbautoactions

If the below legacy folder still exists then also delete it.

/components/com_comprofiler/plugin/libraries/CB/Plugin/AutoActions

I don't know what else to suggest. For whatever reason the autoloader is failing to find CB Auto Actions in your localhost environment. The only way for a localhost environment to properly match a live environment is to use virtual setups (e.g. using Docker) so it's containerized.

That's the version we implemented usage of the auto loader. All our plugins are using the same auto loader behavior so I've no idea why CB Auto Actions specifically is having this issue. Previous versions just duplicated the library files, which was a bad way to do it.

Could I please know in detail the minimum requirements necessary to make the plugin work?
Permissions on folders, necessary php extensions, etc.
I will try to check my configuration, without precise information it is impossible to intercept the problem.

I cannot give you the details you want. I am not a server expert. Standard linux server setup would be ideal, which you can mimic using Docker. It doesn't seam to be your localhost server, but probably your computer. I am using Laragon (soon to use Docker instead) and previously WampServer where CB Auto Actions worked fine out of the box with zero changes to the defaults for both.