Electrical – Replacing 3-way switches with C by GE smart switches

I’m replacing 2 switches in a 4-gang switchbox with C by GE paddle switches. I’m able to confidently identity all of the wires in the box. The first and last switches are 3-way switches; the second and third single pole. I’m only replacing the latter. The first 3 switches share a line wire, the wire being looped around the first 2 and plugged in the third. There are 4 neutral wires capped together and 4 ground wires capped together. One of each came with the line wire, and the other three of each went with the load wires. In starting to replace the third switch, I initially wired the new switch with the neutral and ground wire that went with the load wire. Nothing happened, the switch didn’t power on. Before giving up, I realized I probably used the wrong neutral and ground wires. So I used the ones that came with the line wire. The switch powered on, but the lights didn’t come on, and also I noticed the lights for the first switch didn’t come on (I don’t remember checking the second switch, but I’m guessing it wasn’t working either). So……I guess my question is do I need to add wires (my research is telling me this called a pigtail??) so that each switch, old and new, has their own wires? I feel like I need to do that for the line wire and for the ground and neutral wires going into the new switches.