Full Server issues

Yesterday I took on the task of configuring a full server based on lms 24 (@vasileios). There were some issues such as not being able to set the rDNS (but my provider could change) along the way, but, ultimately I was able to get through it. Unfortunately, there are 3 things that are not working properly and I am not sure how to fix them or if I missed a step or did something wrong.

Item 1: site not secure
My wordpress site shows that the site is not secure. In the cyberpanel it looks like everything is properly set, but, the site does not acknowledge it (in the list websites, it show it has ssl from let’s encrypt)

Item 2: unable to access via ftp
When I attempt to access the server via ftp (with filezilla), I am presented with a message that the certificate is unknown. I do not have an option to select a certificate or make any type of adjustment. I do not understand where the certificate is being retrieved from nor how make updates.

Item 3: dns checker - reverse dns does not match smtp banner
When I run the dns checker, this message stands out to me because of the mention of the reverse dns. My provider told me that it would take up to 24 hours for this to propagate. It has been close to 24, but, not quite (22 hours). I don’t know if more time is needed for this update or if I just need to check with the provider to be sure the information was submitted properly (I will be checking with provider to ensure this information has been updated).

My mail-tester score is 7/10 which has the issues shown in the video (related to new domain).

Any guidance would be greatly appreciated on any of these matters. The most important ones are the first two items; the last item may need help from provider.

domain: magnolialamarpma.xyz

I am reaching out of my comfort zone into spaces I know very little about but I see no answers here.
Are you still having the problems?
I know nothing about Wordpress but the first thing I found in a search about ssl was that Wordpress needs a plugin for ssl.

For Filezilla, it has been a while since I have worked on ssl certs on the server but did you generate your key pair. And did you import your key into Filezilla?
https://www.digicert.com/kb/ssl-certificate-installation-filezilla.htm