... to reward people for filling out my form with granting them lets say a download (file) or provide them a link to such file?
... to limit such rewards (for example only the first 100 who answer get the file)?
Hope you have some ideas and this can be achieved somehow ...
Sorry we do not support this workflow automatically.
The only thing I can suggest is that you ask for their email on the form and then *manually* send an email to the first 100 people who respond with a link to the download.