The only requirement here is that you are a bonafide member.
There is no need to accumulate posts or Goldfingers.
Anyone can join as long as you are a registered member of this forum.
Step 1 - Click your Profile Page.
Step 2 - Go to the MODIFY PROFILE and below that, click GROUP MEMBERSHIP.
Step 3 - Go to the section, AVAILABLE GROUPS and you will see a list of groups of interest.
Step 4 - Beside each group, there is a label that says, JOIN GROUP.
Choose your desired group of interest and click JOIN GROUP.
You're done and you're ready to go.
Good luck and enjoy your ride with the Spies.