of course that won’t work, because you are not following the documentation.
There is a minimum DNS configuration, else Lets Encrypt will not work.
Please start over and read the documentation from the beginning and check you have all requirements met.
ad redirect http to https, have you actually read the part in bold letters? It has nothing to do with Lets Encrypt, and the whole topic is obsolete.
And with so little knowledge about basic server operations, you want to run a really complex mail server?
Prone for disaster…
