Module development and code questions

Hi,

I have spent hours trying to find a way to obtain the values of various fields within a fieldset, but, I have not found anywhere the explanation, to understand it, apply it and then teach others who have encountered the same situation. Could you help me, I'm working with Drupal 9

Thanks

I am using Full Calendar to schedule events for specific User roles (users are applied with different roles). Is there a way to send notification to the users once an event has been scheduled and reminder about the event??  

Scheduler module is something I looked at and it talks more about publishing contents based on timers. Not emails (I may be missing something). Any other module available to help send email to group of users as reminders or notifications? Thanks!

I am building a compound field with (text, url) field, After seeing some of the examples. 

I want to add a number(positive number field min 1 to max upto more than 1000). However I could not get any examples for Drupal 8+. 

Could someone guide how to add number field to fieldWidget and fieldType. 

If possible give any example and the array to create the field inside the compound field. 

Thanks

I have different User roles created and have assigned users and permissions under the roles. Now I would like to create a Taxonomy term that hold the User groups. Once I create taxonomy term, I want to link it with a content type that creates events for selected user groups using Full Calendar module. So is it possible to create a taxonomy term that consist of user roles?

Example: User roles: Group1 (has 2 users and set of permissions), Group2(has 3 users with different permissions)

Taxonomy title: Usergroup

terms: user groups Group1, Group2

My module needs to read and write files in the public:// and private:// folders. In the installation procedure I create the folders and files that do not exist, using the functions \Drupal::service('file_system')->prepareDirectory() and copy ().

At one point in time I added this to mymodule.routing.yml: