Follow this quick Demo Video to create your own WhatsApp Public Group Invite links and in the end of the post you will also find the link to one of Hackology Hacking Group, there is a limit of 256 Members so if you will join after the limit has been reached there is not much anyone can do as you wont be able to join the group
Create WhatsApp Group Invite Links
You can also Revoke the Old Invite link if you want so that all users with old Invite Links will not be able to join if they havent already.
Join Hackology WhatsApp Group through Invite Link
If stuck you can ask about this technique or other in the Hackology Group on WhatsApp