First, the links in the KeypadLinc are required by KPL hardware. A button press does not send an Insteon message unless the KPL has a “Controller of” link record for the button Group number (which is the button number) with the address of the responder device.
The LD2 value in the EZIO8SA link records should be 0x80 to set the output relays to a bit pattern of On/Off represented by the content of LD3. It looks like you took the 0x48 from the command table which is used only if you were actually issuing an Insteon command of 0x48. The KPL does not have the capability to send that command.
In addition, if the EZIO8SA is a recent purchase, the PLM may be one of the newer devices which supports 2000+ links which means the Utility Link Management screen would have to specify Large for the memory size when adding links to the EZIO8SA. The best way to determine the memory size of the EZIO8SA PLM is to do a Set button link between the KeypadLinc and the EZIO8SA. The hardware in the PLM will write the link record in the correct location based on the memory size it knows the PLM contains. You then Display Link Records using the Utility, first specifying the Small memory size option, then the Large memory size option. The first memory size option that results in the Display of the link established with the Set button is the option needed whenever reading or writing link records in the EZIO8SA PLM. You can try changing the LD2 value first. If this does not give a working result, then proceed to do a Set button link to determine the memory size of the PLM.
Do you see the KeypadLinc button LED flash several times when you press the KPL button? If so this means the KPL is sending a message but the EZIO8SA is not responding. This would tend to indicate that the PLM is not seeing the link records that have been written by the Utility. This would support the idea that the link records written into the EZIO8SA PLM were written in the wrong memory location.
EDIT: Although not specifically stated, I assume KPL button 3 is set to non-toggle ON mode and KLP button 4 is set to non-toggle OFF mode. The value for LD3 in the Group 4 responder link should match the pattern specified in the Group 3 responder link (0xFF). Button 3 sends an Insteon ON command, which the EZIO8SA responds to by turning ON the relay numbers that match the bit pattern in LD3. Button 4 sends an Insteon OFF command, which the EZIO8SA responds to by turning OFF the relay numbers that match the bit pattern in LD3. With a pattern of 0x00 in LD3, no relays would be instructed to turn OFF. You could accomplish the same thing with a single KPL button operating in toggle mode. The button LED would be On when the relays are energized and Off when the relays are not energized. Purely a matter of personal choice.