Installing Drupal

I have installed Drupal 10 using the instructions on the Drupal website (https://www.drupal.org/docs/getting-started/installing-drupal).  Everything works fine.  I've been able to add content and manually create simple custom themes.  The problem comes when I try to install contributed themes using composer.  When I try this command (or any 'composer require' command):

composer require --with-all-dependencies 'drupal/bootstrap5:^4.0'

I get this: 

I'm using using Drush 12.5.2.0 and Drupal version 10.3.1 and php version 8.3

drush cr spits out the following error:

Hello,

I am a newbie to the Drupal world. 

In the past, I was able to install Drupal through HostGator's one-click installation directly via the cPanel/HostGator login page. Now it seems to be hidden or removed, and it looks like HostGator is prioritizing WordPress over Drupal. Please advise. 

After following the steps listed here for setting up a fresh Drupal install on a VPS:
https://www.howtoforge.com/how-to-install-drupal-on-ubuntu-24-04/

...I went to install a theme using this:
composer require 'drupal/solo:^1.0'

...but got this error:
./composer.json is not writable.

What steps were missing from that install guide to allow me to install themes and modules with composer?

Trying to alter a content type and getting "The website encountered an unexpected error. Try again later." when I look in the error logs I am getting the error below.

Any idea how to sort this out, I have updated composer with all dependencies but no joy.

[02-Jul-2024 12:40:46 Europe/London] Uncaught PHP Exception Error: "Class "Http\Adapter\Guzzle7\Client" not found" at /home/DOMAINANMR/public_html/core/lib/Drupal/Component/DependencyInjection/Container.php line 261

All help would be welcomed.

Drupal Version - 10.3.0

PHP version 8.3