Yes, it's a pain in the neck doing macOS development. I almost gave up on it at one point it's such a hassle. But once you figure out all the hoops to jump through, it's not too bad. You might want to take a look at my guide to notarizing a mac plugin on my site at https://microbion.co.uk/html/createplugins_r23_3_notarize.htm. This explains the steps needed; the first step is the Apple developer account, which is what I think the tutorial you read must have been referring to. Unfortunately, unlike an Apple ID, getting a dev account is not free.
@m_adam Thanks very much for your comments. You asked which parts of the manual page weren't clear. It's more that it's incomplete, in that it doesn't tell you how to get a bundle ID, app password or provider ID. Also, I don't think the statement that adding a timestamp is optional if you enable the hardended runtime is correct - from what I can see, you must provide a timestamp even though you enable the hardended runtime.
The other thing is that invariably at some point the process is going to fail and there's no mention of what to do when it does. It's extremely frustrating when the notarization fails and you have to figure out why. Apart from that, the page is actually very good - just needs a bit more detail (IMO).