FOSS gamedev and creative worlds

Just got Minetest (its epic) But for some reason I can't join any servers....
It says this for most of them:

Access denied. Your client's version is not supported.
Server version is 0.4.2-rc1
Server's PROTOCOL_VERSION is 12, client't PROTOCOL_VERSION is 13.

I have no clue what this means so can anyone help?

It means that you should use 0.4.1

It just means the servers haven't been upgraded to run 0.4.3 yet. Most still use some 0.4.1 or 0.4.2 release.