Segments and tags?

First I'm not native in English :) 
I'm coming from Active Campaign and find Klaviyo a bit confusing as a beginner here.  I'll try to explain what I need and what my challenges are.

In AC I had the option to add tags to people either on signup (forms)  or manually, based on the tags they went into automation (flows). 

I'll try to explain my setup in AC and hopefully, someone here gets it and can point me in the right direction. 

In AC I had a setup for new clients (webdesign business) where I added a new client manually and added tags to them based on the services have with me.  The whole idea was to send them into automation where they based on the tags got some info/education about the service they bought. 

Say I have 6 services, now I add the client to a list (new_clients) and add 3 services to them with tags, then they go into automation where all 6 services have 3-5 emails. 

Because of the tags, the automation check (split) if they have the tag for service 1, if no, (skip) and go to next option service 2, if yes, they go through the flow (3-5 emails), after that, it will continue and check for service 3 and if they have the tag for that flow etc... 

I like this setup because I just add tags (services) to the user, and then they will go through everything they need. 

I'm sure I can do the same with Klaviyo, I just find it difficult to understand it because there's both lists, segments and tags, and the tags can be added to segments but not to users (profiles).

Is there anyone here can clarify in a simple way how I would do this? Maybe an ex. user of Active Campaign, I understand there should a ton of you guys here :) 

Thanks,
Dennis