To add a Google Maps to Ghost Blog, you can follow these.
#Option 1. Single Map Location
#1. Click Share
#2. Click Embed a map
#3. Click COPY HTML
#4. In Ghost Blog, click the post you want to add Google Maps
#5. Click where you want to add Google Maps and click Plus > Choose HTML
#6. Paste the copied code into the box and click Preview to see the result
#7. Result
#Option 2. Embed Google Maps with custom style/layout
You can use a free tool to create more custom layout/style, like this.
#1. Access this free tool > Choose a desired style > Click Continue with this template.
#2. Enter all locations > Click Add to website for free
#3. Click Publish on top right
#4. Choose Free Plan & Copy Embed code
#5. Use HTML feature in Ghost Blog
and paste your embed code
#6. Result