How can i open and run a project in laravel that isnt mine?

I have to comment and optimize a Laravel project that is made by the previous back end developer that was at the firm im working at. The problem is that i am a junior developer and i dont really know where to check for it. I donwgraded my php version because it required php 7.2.5 or 7.3. I changed the .env db name, host, etc and migrated all the migrations. But it still doesnt work. What should i check next? and where? Its a big project for a consulting website.

it cant connect to the database i think, like i get a white page, no frontend loaded at all, i will paste here the env and a ss to the database:

APP_NAME=your-consult
APP_ENV=local
APP_KEY=base64:93DE6wrEWKiM8q2EtC6TanandzVydkkFPNeSRqYBbeE=
APP_DEBUG=false
APP_URL=http://localhost:8000
APP_API_URL=http://localhost:8000


LOG_CHANNEL=stack

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=admin_yourconsultdb
DB_USERNAME=root
DB_PASSWORD=root

BROADCAST_DRIVER=log
CACHE_DRIVER=file
QUEUE_CONNECTION=database
SESSION_DRIVER=file
SESSION_LIFETIME=120

REDIS_HOST=127.0.0.1
REDIS_PASSWORD=null
REDIS_PORT=6379

MAIL_MAILER=smtp
MAIL_HOST=your-consult.com
MAIL_PORT=465
MAIL_USERNAME=no-reply@your-consult.com
MAIL_PASSWORD=TestareYouCo1@
MAIL_ENCRYPTION=ssl
MAIL_FROM_ADDRESS=no-reply@your-consult.com
MAIL_FROM_NAME=Your-Consult.Com

AWS_ACCESS_KEY_ID=
AWS_SECRET_ACCESS_KEY=
AWS_DEFAULT_REGION=us-east-1
AWS_BUCKET=

PUSHER_APP_ID=
PUSHER_APP_KEY=
PUSHER_APP_SECRET=
PUSHER_APP_CLUSTER=mt1

MIX_PUSHER_APP_KEY="${PUSHER_APP_KEY}"
MIX_PUSHER_APP_CLUSTER="${PUSHER_APP_CLUSTER}"

MIX_URL=http://localhost:8000
MIX_API_URL=http://localhost:8000/api
MIX_API_STORAGE=http://localhost:8000/storage
MIX_ASSETS=assets

MIX_STRIPE_PUBLIC_KEY=pk_live_51HKjElD55LzIx6Do5Cf5tRoklBwZ6DCpo3iA15zN7tDJFTAnOqjAfpgcRwn5apeaYO7Z6iidg3U8QaN6UjW3PLfI001nPJzryy
MIX_STRIPE_SECRET_KEY=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
SUCCESS_URL=https://your-consult.com/comanda-finalizata
CANCEL_URL=https://your-consult.com/comanda-nefinalizata
EURO_VAL=5
PAYMENT_REFERENCE=false

JWT_SECRET=BrDqF6W8G5zkchvFOVIHXmtkRu0n30B1YnwyJWFuObzf8UPRdq7WpDPFozqgHo8i

COMPANY_VAT_CODE=39382763

SERIES_NAME=YC
SERIES_NAME_PROF=PROF
CURRENCY=RON
LANGUAGE=RO

DOCUSIGN_USERNAME=sales@your-consult.com
DOCUSIGN_AUTH_PATH=account.docusign.com
DOCUSIGN_URL=https://eu.docusign.net/restapi
DOCUSIGN_INTEGRATOR_KEY=c2c2099a-0565-407d-826e-dc80a94eae0c
DOCUSIGN_API_ACCOUNT_ID=8c4086f6-d3ab-4d9b-b92d-669a9c2e7433
DOCUSIGN_API_USERNAME=79e0084e-5e71-4de1-b900-4fd8ad7afb7e


TWILIO_AUTH_TOKEN=9a93920b0615907945b31249266c4b1b
TWILIO_ACCOUNT_SID=AC71d96e6a926df0c039acabcfdaad9b23
TWILIO_PHONE_NUMBER=+14439988274

NETOPIA_MOBILPAY_PAYMENT_URL=https://secure.mobilpay.ro
NETOPIA_MOBILPAY_PUBLIC_CERT=live.68FY-TQUB-RU29-67WK-HBGD.public.cer
NETOPIA_MOBILPAY_PRIVATE_KEY=live.68FY-TQUB-RU29-67WK-HBGDprivate.key

BITPAY_PRIVATE_KEY_PATH=bitpay.pri
BITPAY_PUBLIC_KEY_PATH=bitpay.pub
BITPAY_NETWORK=livenet
BITPAY_KEY_STORAGE_PASSWORD=Lamunca123
BITPAY_TOKEN=5WgNp6eNogQXyMYBs5GdSBZ5ePcP7thViD4ZGLZ285Ah

CREATIVE_SMS_TOKEN=I2kPdRTL3pvtH9oX1A25E9vztKvR1U3D4Atx9nmyjVJcceH7fbEjilM1rIhf