Re: I can create a blog but not access it
OK. Thanks to both of you. I was actually already using a WP theme and even after BP and all plugins were deactivated, I still was not able to enter a blog (even on the backend).
So I contacted my site provider and they fixed by re-applying my account’s wildcard settings. I however needed to clear my browser’s cache and cookies before I could reach my subdomains (blogs) properly.
Now back to the prob I was originally trying to address, getting all the posts on the subdomain blogs to appear on my main site page. It is unclear to me if Sitewide tags can actually do this
( see discussion https://wordpress.org/support/topic/one-blog-streaming-multiple-smaller-ones). All posts do appear on the Activity page. The problem would be resolved if I could just get my Activity page to appear as my main page 
Thoughts?
