Short answer
HubSpot's KB strongly recommends the HubSpot All-in-One Marketing WordPress plugin to connect a WordPress site, and says to install the tracking code manually only if you cannot use it. Importing a WordPress blog into HubSpot is a separate tool, WordPress connect, which needs a successful API response from your blog.
1. After connecting
Connected integrations show in Connected Apps. My demo portal's list, with apps that need attention at the top:

2. Check it worked
See checking the tracking code and additional site domains.