Trying to recruit people from FB groups which ought to the perfect place to pull people onto Hive from is like pulling hen's teeth.
I went round dozens of railway and model railway groups trying to recruit people of years ago and it was impossible and I really can't understand why.
Been doing the same with sailing groups and YouTubers recently and they are always begging for Patreon support and tips to fund their channels and same problem.
Getting 1 person is a massive achievement so well done mate!
I'm glad you weren't getting rid of the urban exploring community here as I have a post coming this weekend :-)
Best wishes fella !