To find your Steam group ID, first get the URL of your steam group. It will look something like:
https://steamcommunity.com/groups/nameofgroup
Then append the following to the end of the URL:
/memberslistxml/?xml=1
Which will give you something like the following:
https://steamcommunity.com/groups/nameofgroup/memberslistxml/?xml=1
It will then show you some XML code, at the top of which will have your Steam groups ID, for example:
<memberList>
<groupID64>103249292485930254</groupID64>
Copy the numbers out of the groupID64 tags, that is your groups id.
You can then use that on your Space Engineers server to enable whitelist.
Old Method:
- Make sure you’re a member of the group you wish to find the ID of.
- You must also be signed into your Steam account.
- On you group page, click the invite friends button.
- After doing so, you’ll be able to see your Group ID - It will appear as a long number at the end of your URL bar.