How do people join my space?

You send them your map link. There is nothing to install and nothing to accept. They open the link, pick an avatar and walk in.

On the Free plan

Your map link is public. Anyone holding it can enter at any time, which makes it easy to share, and also means you should keep that in mind before posting it anywhere public. You can customise the link so it reads like your organisation rather than a random string.

On a paid plan

You can close the door. The link itself stays the same for everyone, but you decide who gets through it. Require authentication so visitors must sign in, turn off self-registration so only people you have added can enter, and use tags to decide who may access which rooms. If your organisation already has a directory, company sign-in is the version of this that needs no list at all.