To expand on Newbie's comment:
Modern Browsers such as Chrome and Edge to not natively trust a self signed certificate, so you will get a warning on these browsers. To resolve it so the browser will open without any additional warnings or prompts, install the certificate created in the article on the client machine in the Trusted Root Certification Authorities.
Some additional parameters you may want to add to the New-SelfSignedCertificate:
Expiration: -NotAfter (Get-Date).AddYears(2)
Name: -FriendlyName "My SSRS Server Cert"