"Catalog mode" is not available in 1.5, it is ion development. Please check if you have disabled "Show prices" for that coustomer group (https://prnt.sc/10fv238). Enable this option and check again, the issue will be resolved.
Well, the feature is on our roadmap. As an open-source community, we are trying to add as many features to the system as we can but that happens as per its own timeline. And that's how the open source communities work.
Please turn on the dev mode then reload.
Then give us the screenshot of the error that is shown.
To enable the dev mode to go to your QloApps folder --- > config --> open define.inc.php file.
Then on line 29 change define('PS_MODE_DEV', false);
to define('PS_MODE_DEV', true);