Soapy water only acts as a lubricant, it doesn't have anything to do with sealing. It helps the bead of the tire seated easier on the rim. I personally don't use soapy water, because it gets messy.
First try to inflate the tire to see if it seats properly, you will hear pops as the tire inflates. There will be lots of leaks at this point, both from the sidewalls and from between the tire and the rim. It's ok, but make sure you can inflate to about 60 psi.
Then you can deflate the tire, pour the stan's sealant in, and inflate again. The sealant will seal the small leaks on the sidewall. You just need to shake the wheel until they are all sealed.
If the tire is new, and you can't inflate it, try inflating with a tube first, and leaving it like that for a few hours. That will stretch the tire which makes it easier to inflate tubeless.