If there is no XPM markup at all, it is very likely that the example website is thinking that you are not on a Staging website. When publishing the Settings, there is a flag published, so the Website can distinguish when it is running on staging and generate the XPM markup.
To generate this flag the TBB's rely on the publication target name. This means that the publication target name needs to contain the text: "staging" , for XPM to be enabled on that publication target. You can find this flag serialized on the filesystem in: YourApplicationPath\BinaryData\system\config\_all.json
Probably renaming your Publication Target to something containing staging and republishing "Publish Settings" will solve the issue
Make sure to access yourwebsitedomain/admin/refresh to clear the cache and to restart your appool
Another reason for the button not appearing is usually because the cms url is not properly configured on the Environment Configuration component, located in: \100 Master\Building Blocks\Settings\Core\Admin\Environment Configuration. You need to change this and publish the "Publish Settings" Page