you can now host it on your domain either at https://<<yourdomain>>/apple-app-site-association or at https://<<yourdomain>>/.well-known/apple-app-site-association.
.well-known is a normal directory. just check the spelling of the folder and make sure the AASA file is configured correctly.
Once you do this, use the URL (https://<<yourdomain>>/.well-known/apple-app-site-association) in a postman or website and check if you can access this and see all the contents inside the AASA file.
If this is not helping, please go through the entire steps mentioned in this article and make sure you did everything correct.