So how does this work? Isn't it just like a traditional relationship with a stay at home girl? You pay the bills and that's it or what? If I got a SB over a escort I'd want her to be exclusive with me and for it to be a "real" relationship that I pay for, something where I can get spoiled by her and live my best life so long as I pay all her bills. Wouldn't it be ideal to move to a country like Thailand or Vietnam for that sort of thing? I wouldn't want a spoiled SB but a more down to earth one. Also how commom are mature SBs? I am in my 20s and would be looking for women ages 40-60s.

Props for giving sugar dating a try.  There's lots to unpack in your post, I won't even try to address all your questions.  You are comparing a sugar relationship to:
A: a traditional relationship
B: Hiring an escort
C: Having a Mistress, an exclusive, real relationship that you pay for

 
Sugar dating is none of those things.  I'd describe it most closely as a part time Mistress.  You give her gifts of money and other things, but you are not responsible for 100% of her maintenance.  You see her from time to time, on whatever schedule you both agree on, and the rest of the time you lead your own separate lives.   The relationship is "real"  as you get to know each other well and spend quality time outside the bedroom as well as in it.  Generally, there's no contract, and no strings attached. Sugar arrangements last as long as they last, and ending them gracefully is as important a skill as starting one smoothly. If exclusivity is important to you, that can be negotiated upfront.  But imo, most SBs have multiple SDs concurrently, and vice versa.  Even those who swear you are the only one! They are Timeshare Partime Mistresses.  I hope this is helpful.  I'm sure others here will chime in with their knowledge.

Oh damn I have this already with a nice older lady lol. So a full time exclusive thing is all I'm really seeking

When talking to a girl, you need to be clear on what you want and be ready to walk away.  As I also expect her to only be seeing me, here is my process  

1. Initial contact, message involves her looks, maybe something in her profile and that I'm looking for something ongoing and in person  
2.  If she replies and it seems like we are on the same page. I ask to go to text right away as some sites don't like sex or allowance talk at all.  Plus. You don't really want someone you don't know having these messages on the site.
3. In text, I say hello and ask what she is looking for.  Usually, this will make or break it.  She will often give allowance, time spent. Sex acts in the initial shot.  A majority of answers are, 1-2 hours a few times a month and a rate.  I'm often times not going to agree with the amount desired.
4. I will say I'm looking for a few dates a month with someone I can have a great time with.  She needs to be loyal, charming and a lot of fun.
5.  We usually go back and forth on allowance, I will always say it depends on what you are open to.  Get her to say if she's willing be exclusive, go raw, what types of sex she's open to, etc.  Only do ppm to start.  Mention you can go monthly if you two really have something special after a while.
6. At that point, if we are a match, I'll set a first date.  Somewhere public.  Spend time getting to know her, with the option of BCD if she checks out.  If she lives far, video chat in advance.  Often times you'll find out she's a scam right there.  If she's not willing to video chat up front, says she's shy, has phone issues, don't do the meet.  She's gonna hit you with some lame excuse of needing gas money up front or needing uber money.
7.  Have the date.  Keep your Spidey senses on.  If she seems off, pics are really old, etc.  feel free to bail, pay for the drinks or meal.  Many girls have managed to hide their body on the camera well enough to not show they are fat.  Or used pics that are 10 year old and 2 kids ago.  Or just acted really weird like they are on drugs.  Or, last minute, demand a higher allowance or not agree to what we had originally agreed to.  And absolutely do not pay up front!
8. If it's a hit, set up the next date before you two depart.  Many girls are flakey and just want to hang when rent money is needed.  Meaning they have a book of SDs and how much they pay. IE not going to ever be exclusive.

This is all good, standard advice.
But if you're in your 20s and looking for a 40-60-year-old SB, that is ... highly unusual. It's more of a cougar-cub thing that you might find in one of the kink-related forums. If you have decent looks and funds, you should not have trouble finding someone.
The more typical SD is quite a bit older and has been through relationships or marriage (and has had time to accumulate wealth), and often wants to find a more youthful partner. Obviously something for everyone out there, but I think the most common dynamic is the older guy and younger babe seeking each other.