Smartthings integration help

Hey guys !
I really need your help to understand if I’m dumb (probably) or if I’m doing something wrong (probably).
Short story, I install hassio on a virtualbox and everything is working perfectly. Then my goal is to bring my smartthings in hassio.
So first has I understand I need to have a nabu casa account, so I created an account and start the trial. Then has I understand I need to set up a base http in the settings? So I set the base http to the address nabu casa is giving me. But when I want to integrate smartthings and I copy my token create in the smartthings token website its said it’s not working because of a smart app error… so I dont really understand what I need to do. I was thinking nabu casa was giving me a https address with a certificate and smartthings app would work ? Same on the smartapp I’m not able to bring my home assistant:(

I hop you can help a beginner like me. Thanks a lot !

These two issues seemed to come in back to back.
I wonder if they’re related.

Unfortunately I turned off my SmartThings integration a while ago.
I wonder if there’s something going on with their switch from the classic app to the new one.

That’s why I abandoned ship to Hubitat, SmartThings was content to remove existing functionality without providing a new path to update existing apps and drivers.
Good luck.
If nobody helps I can see if I can replicate this with just virtual devices, while the IDE still exists…