I contacted Salesforce support and unfortunately Salesforce won’t read the “authorization” header because Salesforce filters-out anything having to do with “authorization purposes”. The solution proposed by Salesforce support is to pass the value in a header of a different name (anything other than “authorization”).
Thanks for following up about this. Unfortunately, we don’t have a method to provide webhook verification through another header. I can reach out to our engineering team to see if there there are any options here.
If you would like to look into that, please send an email to developersupport@zoom.us with a link to this thread.
In the interest of keeping the solution public, we do not have any alternative methods. Instead a 3rd party endpoint should be used which works with the SFDC API.