Use the installer requirements screen and resolve any failed checks.

Step 1 checks the required PHP version, PHP extensions, and writable directories before Continue becomes available.
The first installer page is titled 1. Requirements Check. It displays separate tables for PHP extensions and writable directories.
| Area | What it shows |
|---|---|
| Extensions | Each required PHP feature and a status indicator. |
| Directories | storage and bootstrap/cache with a writable-status indicator. |
| Continue | Enabled only when the complete requirements check passes. |