Unifi Captive portal & Chrome Browser issue

Hi , I wonder if any of the wise heads in here can help me resolve an issue I am having with the chrome browser and the unifi captive portal . I have the cloud controller setup in a self hosted cloud with a unifi access point at the clients site , The redirect to login works on all browsers and mobile devices except chrome . From what I have managed to find on the web this is because chrome sees the redirection as MITM attack. I found this document which describes what I am seeing Captive portal handling for HTTPS requests - Google Docs .
However I am stumped as to how to resolve the issue .
Any help you guys are able to offer would be greatly appreciated , thanks in advance.
I’m sure this has been answered before but I can’t find it.

I just did a video on Captive Portal and pfsense and one of the things I note is that Chrome does not like HTTP captive portals which is why in that video I show using a valid Let’s Encrypt certificate. I am not aware of any built in way to install certs for UniFi and their captive portal.