The module can't be downloaded into a 8.9 project

[kmn0]

You can not download the current module to include it directly from the appstore into your 8.9 project. So I first I downloaded Scheduler_v1.4.0_8.3.0_20191118.mpk on my file system and opened it using the 7.23.7 modeler, but there it says the module could not be imported because it was created with a newer version (8.3)
However, you can import the downloaded module from your filesystem into the 8.9 project, so that is what I did.
I expected the imported module to appear in the App Store module node in my project, but it appeared as a (regular) module in my project, is there a way to change that?

[jaspervanderhoek]

The reason why the 8.3 version from Github isn't in the appstore is because I haven't been able to go through a full test run with this updated version. I'm assuming it works, I didn't make breaking changes and basic scheduling worked, but I only publish in appstore after a full test. It's been a while since I last looked at it, so I'll try and do this soon.

Part 2 of your question, unfortunately you cannot classify a module as an appstore module. The only way the modeler considers this an 'appstore' module is if it is directly downloaded from the appstore.