Maybe this will help you:
Your error-message says:
[Tue Dec 15 19:28:14.223489 2020] [:error] [pid 15987:tid 47366492501760] [client 67.60.168.59:62328] [client 67.60.168.59] ModSecurity: Access denied with code 403 (phase 2). Match of "within %{tx.allowed_methods}" against "REQUEST_METHOD" required. [file "/etc/apache2/conf.d/modsec_vendor_configs/OWASP3/rules/REQUEST-911-METHOD-ENFORCEMENT.conf"] [line "43"] [id "911100"] [msg "Method is not allowed by policy"] [data "PROPFIND"] [severity "CRITICAL"] [ver "OWASP_CRS/3.3.0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-generic"] [tag "paranoia-level/1"] [tag "OWASP_CRS"] [tag "capec/1000/210/272/220/274"] [tag "PCI/12.1"] [hostname "cl.d4x.biz"] [uri "/remote.php/dav/files/joe/"] [unique_id "X9lwvuqswoJmV4OkecvnoQAAAIU"]
So in file
/etc/apache2/conf.d/modsec_vendor_configs/OWASP3/rules/REQUEST-911-METHOD-ENFORCEMENT.conf
I would try to disable line 43 [id 911100]
and see what happens.
Also you should of course get in touch with your service provider (cpanel?) . They should be able to help you.