This is a tricky one... I don't think you can currently automate it entirely end-to-end, even with Zapier, though that might be possible in the future. However, you can automate parts of it to save you time.
Guest booking comes in
I email the HOA
That's easy - you'd set up a template configured to email the HOA directly (instead of the guest), including the necessary information from the booking using our field codes, and triggered on either the "Booking is created" event or possibly the "Rental agreement is signed" event if you are gathering information there that is required by the HOA. This would be somewhat similar to the "Reminder to Myself" sort of email discussed here, though sent to the HOA not you:
https://www.ownerrez.com/support/articles/reminder-to-myself
HOA emails me the codes
I then copy and paste that into an email and send it to the guest
Yes, you're going to be doing copying and pasting. However, you could save some time in not actually creating the emails yourself.
First, create a Booking custom Field Code for the gate code:
https://www.ownerrez.com/support/articles/custom-fields
Then create an ordinary email template and trigger to send the code to the guest, using that custom field code, just a day or two before arrival. It would be very similar to the "Pre-arrival door lock code" in our template library:
https://www.ownerrez.com/support/articles/email-template-pre-arrival-door-code
The only catch is that you have to manually copy/paste each code from the HOA email into each individual Booking, into that waiting empty field code, which is on the Custom Fields tab of each Booking. If you don't, they'll get an email with no code. But this should still save some time.
