At first download Installable WordPress file only from Download Tab.
Then follow step by step instructions:
- Login to your WordPress site’s administration area
- Navigate to Appearance > Themes > Add New > Upload theme
- Click on the “Add New” button, then click on the “Upload Theme” button and also check below image
- Upload the theme zip file named grassy.zip
- Click “Activate”
If this method fails we recommend uploading the theme via FTP. Open your FTP client, move to your WordPress installation path /wp-content/themes and upload the unziped grassy folder.
After the upload is complete navigate to Appearance > Themes and activate the theme.
Install the child theme
Main download folder includes a child theme. A WordPress child theme allows you to apply custom code changes to your site. Using a child theme ensures your customizations will not be overwritten, even if you update the parent theme.
You can same way install child theme as like parent theme. You will get child theme under main files and name is grassy-child.zip