Manual Template is a responsive template, so it can be used for both desktop and mobile devices. But Blogger has a default template for mobile devices, so we must disable that default template to allow Manual Template can display on mobile also.

To do that, access your blog dashboard, choose Template tab and click Gear button.
How to enable responsive feature for custom Blogger template - Access?

In Choose mobile template drop list, opt in "No. Show desktop template on mobile devices"and click Save.