Best practice when mass creating user accounts.

Hello everyone. I am writing here because I find myself in a pickle. I am expected to have a system running for 200 users. They will only be filling a simple form several times and we will be gathering the data. Now the problem is our users are both unmotivated and really old to go through the hassle of registering an account. Half of them do not own a decent smartphone. The project leader can’t gather their 200 emails so we cannot register them or put them in the database manually.

We do not want to create usernames like so: user1, user2, user3, etc and give them passwords which are difficult to type. We also dont want to make it easier for user4 to guess that there is a user3. If we had the emails we could sacrifice a dev’s time to enter those and give them all the same password at least or for some increased security do a an array of a dozen easy strings and randomly chose two and concat them or some such lazy leg work.

I am curious if anyone has been in the same situation and has a tip or two about how to deal with mass assigning usernames and passwords to a computer unfriendly demographic.

Thanks