Not sure I understand what you mean by that… the Kaltura RPM and deb packages declare all needed PHP dependencies and they will therefore be retrieved automatically. You do not need to manually install any PHP packages in order for it to work.
In regards to
Please see Centos7 update dependency error
In regards to MySQL vs. MariaDB, this is mentioned here:
This is correct. Added https://github.com/kaltura/platform-install-packages/blob/Lynx-12.12.0/doc/install-kaltura-redhat-based.md#installing-on-aws-ec2-instances.