With that in mind i think you're heading in the right direction looking at your screenshots.
You are using the action "Create an agreement from an uploaded document and send for signature"
this expects the documentID from another Sign action "Upload a document and get a document ID"
That step requires some file content wich can come from a Sharepoint Library or OneDrive.
The file/document should be quite straight forward.
What is a bit more tricky is to accomodate all your signers, though it looks like you have that sorted. The property which determines the signing order is in the participant json. In your screenshot it's "order":1,
As you want all signer to receive the agreement at the same time, just leave this to 1
This json is documented as part of the Rest api here
overall the end goal is to end up with a variable containing json like below. This is an array of participants. Below shows 2 sets, in your case yo'd have 5-20 sets in this array.
[
{
"memberInfos": [
{
"email": email1
}
],
"order": 1,
"role": "SIGNER"
},
{
"memberInfos": [
{
"email": email2
}
],
"order": 1,
"role": "SIGNER"
}
]