FirstDatabase is a placeholder
Does it have any collections? i don’t think
That may be the reason list_collections is erroring
Coming back to your cluster status just click on clusters.You will see green icons and you will see a primary and two secondaries
Also at bottom of that page you will system status ok
Also click on database access.You should see the users created in database with privileges given to them
Can you connect to your database from shell?
From cmd prompt of Windows
try this
mongo “mongodb+srv://tudor_15:Centurion15@cluster0.acapz.mongodb.net/myFirstDatabase”
Have you whitelisted your IP? allow access for all