What is the estimate number of users moralis free plan can handle

What is the estimate number of users moralis free plan can handle concurrently,
We are building a decentralised streaming platform and we need some of our whitelisted users to test some functionalities before going live.(we want to use their experience here to perfect our product)
All they would do is authenticate and sign a transaction.

Free servers can handle unlimited users, but if many users are requesting the API calls it will hit the API rate limit.

maybe hundreds, it also depends on what the server does

Like I said the users will just authenticate, sign a transaction and lastly query a row to get the number of people they have referred.
All sync are also turned off.
It is important I add that I have seen the CPU reached 100% a couple of times with just single user(me) though it usually corrects to like 18% seconds after that

on a free server you can see the CPU going to 100% from time to time for other reasons too, like when it is doing an automatic database backup, as it has only one CPU core