Sangoma Centos is very old and it’s used on FreePBX 16. The current version of FreePBX is 17 and that uses Debian. I’d suggest you try Debian on the Lenovo then FreePBX on that.
If you must use FreePBX 16 then there is another way.
Install Ubuntu Server on the PC - and you might consider putting at least 2 drives in the PC and setting up software mirroring, which is very easy to do during the Ubuntu Server installation.
Then once it’s all configured the way you like, install KVM than install Sangoma CentOS in a VM