First of all I am sorry you had such a bad experience. Please take a look at the linked documents here
The omp tool got deprecated several years ago. We provide gvm-tools as a replacement.
Disclaimer: Greenbone isn’t responsible for any packages shipped by Linux distributions. Therefore we also aren’t responsible for your CentOS packages. I guess you should report problems at GitHub - Atomicorp/gvm: Greenbone Vulnerability Manager / Openvas packaging project