We need to install a client of Dynatrace 6.1 in a computer Apple Mac OS but in the Downloads Page the latest release available is 6.2:
¿Where can I find the instalables for the previous version 6.1?
That is probably no longer available there as 6.1 has been end of life since late February (even 6.2 isn't supported at all since June so that might be disappearing too shortly). I'm not aware of any other Dynatrace maintained locations where this would be available still.
I would strongly recommend upgrading to one of the supported releases.