From the wiki rules section
220.127.116.11. Must be limited to 6 clients if standard IEEE 802.11 protocols are used.
18.104.22.168. Must be limited to 8 single polarity clients if Nv2 or Airmax is used.
22.214.171.124. Must be limited to 12 dual polarity clients if Nv2 or Airmax is used.
126.96.36.199. Signal strengths must exceed -73 dBm for new clients to connect.
188.8.131.52. Signal strengths must exceed -75 dBm for existing clients to remain connected.
184.108.40.206. Clients must maintain a 95th percentile CCQ of 60% or higher in both directions to remain connected.
Atlas has two Mimo Dual polarity sectors so can host 24 clients, the clients needs to face the sector they are connecting to.