Data volume and mobile workers volume

I want to know that what is the data volume of this app or how many data store on this app in a time or during data collection period.
Other concern is that how many mobile workers can enrolled for one web user.

You might find some of the information you're looking for on the pricing page:

There is not a relationship between the number of web users and mobile workers - you could have one web user and as many mobile workers as you like. Mobile workers are limited in number by the plan, however - see the pricing page for details.

None of the plans limit the data that can be stored by your project.

If you're more worried about how much data will be stored on each mobile device, that depends entirely on the way your application is set up. The system is set up to function entirely offline, so typically projects will be configured so all data that each mobile worker needs is available on their device, but not data from outside that mobile worker's district.

in free trial i want to know about those message

The free trial includes up to 5 mobile workers

I'm in the way to a survey program. I have at list 40 enumerators for using tablets and data collection from field. There will be 50 thousands household and may be data will be 2 lakhs over. Is this possible in free trail verson ?