SUCCESS!!! I now have my Blogger (blogspot) site as a subdomain of my Go Daddy hosted Webflow website.
Main website: GoDaddy hosted Webflow created website
Blog sub-domain: blog sub-domain
Here are some instructions for how to do it:
This site gave the best instructions for what to do on the Blogger side: redirecting Blogger to be a subdomain to your site. CAUTION: In their example they used the domain site as the destination. If you want it to be a sub-domain instead (like my site) then be certain to enter blog.yourdomainname.com in the white block provided. (No www's or https or slashes). Stop at end of step 4.
Now it is time to address your GoDaddy hosting site.
Log into your Go Daddy account.
Go to your My Accounts page.
In the DOMAINS section click on the Manage button
In the right corner you will see four squares next to a hamburger icon - click the hamburger icon to get into "list view".
Click on the blue domain name you want your blog to be a sub-domain to.
You should now be in the Domain Details page.
Click on the DMS Zone File tab
Click on Add Record
A separate box will open up asking you to select Record Type
In the drop down menu select CNAME (Alias)
Now you start following the Blogger instructions
In the HOST field enter the word: blog
In the Points To field enter the info Blogger gave you
Leave the TTL unchanged.
Click the ADD ANOTHER block
Enter what Blogger gave you for 2nd HOST field
Enter what Blogger gave you for the corresponding Point To field.
Click the Finish block
I can't remember if there is a Save Changes - if there is then go ahead and Save.
You're all done.
Go Daddy officially says it can take up to 24 hrs for the changes to take affect - but it happened within 30 min for me.