I’ve built this out many times in many ways.
If you need help knowing why your setup isn’t working seeing workflows would help.
Create 2 data types called campaign & campaign steps.
You’ll also need an option set for “step type” and “step duration” that is stored under campaign steps.
Duration consists of minutes, seconds, hours, days.
Type consists of all your integration types, in one of my cases that was task, email, vm drop, auto dial, sms.
Your UI/UX will allow them to add a new campaign action and select from a dropdown of option sets for (send after _____ “step duration”)
So they input let’s say 1 in the input and select drop down for “day”. That step will send 1 day after the trigger.
Once they finalize you’ll use a series of conditionals, backend workflows, and scheduled actions to execute.
If the “send after ____ step duration” isn’t a flow you’re looking for you can also use a GHL approach that uses “wait” step types.
Beautiful UI you’ve built by the way🙌
Side note: my drag and drop email builder will allow your users to make some beautiful campaigns 
If you need additional 1:1 support I do offer paid consulting. Feel free to schedule a call if you get stuck.