The iApp won't stop working, it is just being deprecated. I just downloaded the latest iApp templates from downloads.f5.com and it included the AWS HA iApp, with a helpful ReadMe txt file that included this line: "The planned EoSD/EoTS/EoL date for this iApp template is 12/31/20." Also, you can check out this KB article for details about iApp deprecation: https://support.f5.com/csp/article/K13422.
Good job on starting with the CFE! I'll gladly help you out over email and we can set up a call if needed. I'll shoot you an email now.