First you need is to download and install the Notable app from the official website. Then download the workflow file and install it in alfred. But you need to purchase powerpack before running this workflow. By default this workflow will create markdown files in ~/.notable/notes folder. If you want to change it, add an environment variable named notable_folder in the workflow.
Press alt+space(or the shortcut you have selected for alfred). Then type note Name of my note.
Then it should create new markdown file named 2020-07-13-name-of-my-note.md inside noteable direction.
By default the markdown file will be generated with a basic template. If you do not want to use a template, then add no_template in environment variable. You can use your custom templates as well. Just add a template.txt file inside notable app's notes directory(where the markdown files are being created) with your favorite markup.
Feel free to contribute this project. The python file used here is attached with this repository.