Hey Matthew,
This seems your Website hosting problem. Make sure
- You have created a database
- You have create a user for that database
- You have password for that database user
- You have connected the database with user.
- Your database host is accurate in most cases its localhost but sometime its different as well.
Then you can run the installation and it should work! If still database access is denied that means there is some problem in hosting end.
Also try to upgrade your web hosting to PHP 8.xx that is very good and fast php version.
If still not sure, you can get web hosting services from us for only 5$ per month for 5GB with cPanel and 2 months free of cost.
If you need more help in installation you have to send your web hosting logins , we will reply tomorrow thanks