What errors are you getting?

The storage limit on hobby plan is 5GB

the database shutdown automatically and failed, it because of free plan

Oh, so you reached the maximum storage limit on trial plan? Makes sense

I have the same problem
MongoDB crashed
Database Connection

We are unable to connect to the database over the public network.
Should I update the plan?

are you on the free plan? have you reached the storage limit your plan allows for? if yes, then an upgrade would be required, once upgraded you can go into the volume's settings to grow the size of the volume

I have not reached the storage limit, I only have one table since I am just trying railway but I am worried that it will crash

after all it's just that, a trial. you can always upgrade and grow the volume at any time!

So it is most likely that the crash is due to the trial?

it is a possibility