transferring subscribers from old wp.org blog url to new wp.org blog url

Hi. We recently moved our company website from DNN to www.ads-software.com: https://www.calipercorp.com. Our blog was a separate wp.org site at https://calipercompetitiveedge.calipercorp.com. but we have decided to incorporate the blog in our new website rather than have it on a separate domain. In order to keep our current 400 subscribers, via Feeburner, I’ve seen suggestions to change the original feed url to the new feed url. I’ve tried this but I must be doing it incorrectly because it’s not working. I’ve tried a whole bunch of the suggested wp feed url’s but I’m getting this for every one I try:
FeedBurner
Received HTTP error code 400 while fetching source feed.
Identify Feed Source
Back to My Feeds
The feed URL you entered is:
https://calipercorp.com/feed=rss2
We could not find a valid feed at that address. Here are some possible reasons this might have happened:

How can I set it up so that I keep my current subscribers, especially my email subscribers, so that they automatically receive an email with each new blog post on our new website like they used to on the old blog site? Thanks so much! (Sorry, I’m not terribly tech savvy.)