Serome Could explain your set up in more detail?
You say, "is a rural area of Colombia, there is no internet connection". Then how do the users access their mail?
Also, "there is currently an online platform". What have they been doing if there is no Internet connection?
"the idea is to provide the service to places like these where there is still no internet access through devices such as raspberry pi 3b+." So the networks the users access will be each an "island", isolated from the Internet.
What is the cloud in "I have more than 100 users to see from my Moodle in the cloud"? In any case, it is something which you need to see, not the users (who are sitting in classrooms with no Internet access)?