By default, and exception made for OWNER/(SUPER)ADMIN/LEADER, your bebot will see anyone unknown to him as ANONYMOUS for obvious security reasons.
But you may need to open it for public use.

This could be done by changing code and/or database access level of, e.g., !join command as anyone will be seen as GUEST once in chat, thanks to the corresponding option under !settings security ... but this way of doing could be
problematic, hence we don't recommend ...

Better recommended way for this is to filter by the !security/!flexible system and set of commands. Let's take an example that you need to set your bot opened to anyone over level 100 :
1/ create a new group, eg => !addgroup anonjoiners public
2/ allow this group to receive flex condition(s) => !flexible create anonjoiners AND
3/ set the wanted condition(s), eg => !flexible condition add anonjoiners level > 100
4/ set the group level to GUEST => !security levels => click on GUEST link in front of anonjoiners (that was ANONYMOUS by default, for security reaons).
From now on, you bot will accept any joiner over level 100.

NB : on the same principle you could cumulate several conditions (either under AND otherwise OR associativity) checking over specific rank(s), player(s), org(s), profession(s), etc.

You may even want to include some sided check(s) :
5/ register the group => !set Flexible_Security Guest_Group anonjoiners
6/ (re)set the level => !minlevel 100
7/ set the side(s) => !faction neutral
From there, you bot would only accept neutrals over level 100.

Feel free to check these commands notices (with !help commandname) to find the best way to make your own settings according to your needs !