Hi, sorry for the delayed reply. Your validation is most likely failing because you are trying to validate both *.isemanhomes.com and isemanhomes.com, due to the way Let’s Encrypt validation works this requires updating the same TXT record with 2 different values. Some DNS control panels allow this, others don’t. One option is to let one validation pass then get the other one to pass over multiple attempts, then because LE cache validation successes you will eventually be able to proceed.
I don’t recommend using the Manual DNS option at all as it requires you to not only remember to renewing your cert but also to remember how to do it and endure the possible failures you can encounter, I’d advise you to try our Rackspace DNS provider and provide feedback if it doesn’t work for you. Alternatively, check out the acme-dns option (https://docs.certifytheweb.com/docs/dns/providers/acme-dns)