Here are a couple screenshots of what you should see based on my following the same instructions provided by adiantek.
First, there should be a folder (created by you) named 1.17-aarch64 under %appdata%.minecraft\versions\ as shown below. And yes, there should be a corresponding entry for it in the client under the Version dropdown list when you go to create a new installation.

Below is what you should see in the 1.17-aarch64 folder (once the launcher downloads the jar file; probably after you create an installation with it the first time):

Finally, this is what the installation looks like once you've created one and edited the Java executable path. Your native ARM64 java path might be different than mine, so be sure to pick the correct location when you edit this path (I used the Microsoft distribution of Java 16, but there is at least one other out there that has ARM64 builds):

I was originally confused about setting up a custom version too (never did it before), so hopefully some visuals will help.