how to troubleshoot PASE errors?

what are basic troubleshooting steps for PASE errors?

following Aaron's instructions on using Lets Encrypt.
https://www.mcpressonline.com/security/general/techtip-lets-encrypt-together

I run these steps:
call Q2TERM
git clone git@xxxxxxxxxx:Neilpang/le.git

on a V7R3 system I get:
#

git clone git@xxxxxxxxxx:Neilpang/le.git

Cloning into 'le'...
Host key verification failed.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
#

how should I go about troubleshooting this error?

on a V7R2 system I get a different error:

git clone git@xxxxxxxxxx:Neilpang/le.git
Cloning into 'le'...
error: cannot run ssh: No such file or directory
fatal: unable to fork

the PATH is the same on both systems:
echo $PATH
/QOpenSys/usr/bin:/usr/ccs/bin:/QOpenSys/usr/bin/X11:/usr/sbin:.:/usr/bin

how to find where SSH is installed on the V7R2 system? 5733OPS is
installed. Options 1 thru 15.