→ Processing Dependency: libstdc++.so.6(CXXABI_1.3.9)(64bit) for package: pritunl-ndppd-0.2.5-1.el8.oraclelinux.x86_64
→ Processing Dependency: libstdc++.so.6(GLIBCXX_3.4.21)(64bit) for package: pritunl-ndppd-0.2.5-1.el8.oraclelinux.x86_64
This is likely from using the wrong repository. That package is for RHEL 8 based distributions, if it’s Amazon Linux that will need the Amazon Linux repository. Check the repositories documentation for the correct repository.