How to Install WordPress Theme on WordPress.com Business Plan
If you’re on WordPress.com business plan, the installation method is a little bit different.
Step 1
Under Personalize tab, click on “Themes” (do not click the “Customize” menu)
Step 2
Click “Upload Theme”
Step 3
Upload Genesis.zip first
Repeat Step 2, and then upload the child theme (childthemename.zip, example: yoon.zip or bloom,zip, etc)
Activate the child theme.