cant add new themes in joomla 4

YOUR_TEMPLATE_NAME will be different for your site. It's the name of the template you are using for your site, which may be "cassiopeia" (if you're using the default Joomla template). You can look at your admin -> templates area to see what is enabled and then look at the names of the directories in the /templates/ folder to find the correct one.

I hope that helps,
Alex

If it's not there, create those folders and drop the template files in there that you want to update.

For more details, please see the Template Override instructions for the SCLogin module:
www.sourcecoast.com/sclogin/documentation/themes

That includes the note:

To create a template override, you'll first need to create the following directory:
/templates/<YOUR_JOOMLA_TEMPLATE>/html/mod_sclogin/themes/

Glad to hear we could help!

Thanks,
Alex