Application set up with Azure SSO gets 502 error on the redirect

Question

We have a VM setup in our Azure environment that hosts a Filemaker Server (for those who are familiar with Filemaker). We have configured the proper configurations with in Filemaker, and registered our application in Azure, creating Client Secrets for SSO and setting up our redirect URI. When users attempt to sign in the with SSO in our Filemaker Application, 502 - Web server received an invalid response while acting as a gateway or proxy server, is returned. Any information as to why this is being returned would be helpful.