Andrew,
Do I understand correctly that you were able to install Webwork 2.15 on RHEL8?
Have you used the install script? I tried to follow and modify the steps for ubuntu using perlbrew with perl-5.20.3 and compiling libapreq2, mod_perl2, but then even openssl-devel looks incompatible to Net::SSLeay. I am not sure how many other things would have to be compiled from source.
Andras