@negarahmady
Hi, thanks for reporting this. The install failure was caused by a dependency version mismatch in the API Platform packages we rely on. We've fixed it and published a new release (v1.0.5) that pins those dependencies to a compatible set.

Please pull the latest version and run the installer:

composer require bagisto/bagisto-api php artisan bagisto-api-platform:install

If you have a partially-installed/old copy, run composer update bagisto/bagisto-api first, then php artisan bagisto-api-platform:install.
Let us know if you encounter any further issues.