HA installation ISO

I have a server with 1.2Tb HDD but when I install iso FreePBX with “HA Install”. Centos takes on HDD only 300Gb.

How can I increase space on HDD for system.

That is correct as when you activate your HA license it will create the rest of the disk inside the LVM setup. If you are not going to purchase and use HA then install without the HA option and it will use all the disk by default.