That's quite a laundry list .... so we'll take it slow and one at a time.
Debug screens are usually in yellow background with 1 or 2 boxes of text info ... one called a 'stack trace' ... so no debug info ... which is good in a way ... means mis-configuration or not configured properly.
Shared too much ... usually not good to copy and paste a log ... like live log output ... give too much info about your site. Next time ... just plain text ... no url's are clickable.
First - php
opcache is an extension to any version of PHP. Moodle sites do run better if Zend-OpCache is enabled. Where you host, probably in cPanel (or DirectAdmin - your hosting provider has both?), there is an icon/app that allows you to choose which version of php to use with a domain (a site) and what extensions to use. On some cPanel systems it's called 'EasyApache' (kinda a misnomer cause its about PHP ... an apache knowing what extensions are available.
You are hosted with https://www.hawkhost.com/ ...
They have a Knowledge Base:
Searching it I've found:
which is how to use Easy Apache. Maybe it's what you can access ... maybe not ... but do go check it out .... remember ... version of php per domain and what php extensions ... you want php-opCache turned on/checked.
Once you turn it on, Apache has to be restarted for it to know about PHP version change and the loading of PHP Opache. Restart apache.
Then go back to your moodle and see what it says - same environment check.
Now a beginning for the others ... the environment check said you are running 3.8.x ... so docs you should read at Moodle.org are docs for that version. In the url you shared it had 39 ... Read this:
That enough to mull over for now?