They can post links, but I believe there are limits (2 per post maybe?) for level 0 users. Its a spam pervention technique.
I don’t think we want to open it up to allow a post full of links, but it can be tweaked. There’s probably discussions out there of what a good number is. Afaik we are still using default trust 0 settings.
From the sounds of Understanding Discourse Trust Levels all they need to do get to level 1 is read some past posts, which I think before asking questions, people should do to confirm they are not asking the same things.