AWS lightsail ssh server problem "Server refused our key" & installing a website demo on pc -- 2

1- I can't connect the lightsail ssh by putty with the default ssh key
"Server refused our key"

2- localhost demo website error - all xampp and other software are ready but can't start the "PHP artisan serve" and connect the database.

Error msg
During inheritance of ArrayAccess: Uncaught ErrorException: Return type of
Illuminate\Support\Collection::offsetExists($key) should either be compatib
le with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTyp
eWillChange] attribute should be used to temporarily suppress the notice in
G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Support\Colle
ction.php:1349
Stack trace:
#0 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Support\Col
lection.php(11): Illuminate\Foundation\Bootstrap\HandleExceptions->handleEr
ror(8192, 'Return type of ...', 'G:\\My Drive\\web...', 1349)
#1 G:\My Drive\web\Beta\vendor\composer\ClassLoader.php(478): include('G:\\
My Drive\\web...')
#2 G:\My Drive\web\Beta\vendor\composer\ClassLoader.php(346): Composer\Auto
load\includeFile('G:\\My Drive\\web...')
#3 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Support\hel
pers.php(110): Composer\Autoload\ClassLoader->loadClass('Illuminate\\Supp..
.')
#4 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
PackageManifest.php(89): collect(Array)
#5 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
PackageManifest.php(78): Illuminate\Foundation\PackageManifest->config('ali
ases')
#6 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
Bootstrap\RegisterFacades.php(26): Illuminate\Foundation\PackageManifest->a
liases()
#7 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
Application.php(230): Illuminate\Foundation\Bootstrap\RegisterFacades->boot
strap(Object(Illuminate\Foundation\Application))
#8 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
Console\Kernel.php(310): Illuminate\Foundation\Application->bootstrapWith(A
rray)
#9 G:\My Drive\web\Beta\vendor\laravel\framework\src\Illuminate\Foundation\
Console\Kernel.php(127): Illuminate\Foundation\Console\Kernel->bootstrap()
#10 G:\My Drive\web\Beta\artisan(37): Illuminate\Foundation\Console\Kernel-
>handle(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\C
omponent\Console\Output\ConsoleOutput))
#11 {main}





You need to connect my computer to fix this problem with a chrome remote desktop.