Hi,

For sure we need more informations:

1. What template you installed?
2. What Joomla version you have?
3. What PHP version?

I installed the https://demo.joomshaper.com/?template=arino template. Right after installing it. I clicked to delete install folder. The clicked the site link and the website came up just fine. I went to log in the administrator page and the page has "ERROR 500 - INTERNAL SERVER ERROR" accross the page. Need help

PHP version 7.4 and Joomla version is the version that came with template. I haven't had a chance to update joomla in admin area yet

All permission on folders are 0775

You installed Quickstart or just a template on current website?

I need only this info.