I think that KirbyDE hasn't included any modifications for the postbit_legacy template, because I haven't given him any. I'll have to look at this and come up with some instructions. Give me some time.
Ah, OK, it shows version 1.0.4 which should be equivalent to 3.5.4. No need to re-download the file again, I do not think that KirbyDE has updated it.
As for the User Away hack, this is the vB 3.0.xx release:
https://vborg.vbsupport.ru/showthread.php?t=67250
Rgds