After hours of trying we have decided to post this. Proxmoix 6.21 installation works find if you do not specify the partitions sizes and go with default. However following the documentation:
If we make changes the installation leads into the following...
Primary > 1 SSD Disk 1Tb (I want to use OS , Proxmox and VM , 1 or 2 snapshot)
Secondary > 1 HD 2Tb (I want to use for Backup , ISO and snapshot)
1 VM : 700Gb
Free Space for future VM expanding : 200Gb
In the installation I want to use the max possible space for VM