I'm required to create a way for users to be able to create sites (self service). I'm using a form with a power automate. I have created a site script and a site design. When i follow the instructions here using Power automate

Its using the OOTB site design. The question is will it be also use a custom site design i have created in the tenant?

I tried using a GUID for my custom site design but it seems not to work.

Any ideas?