So heads-up that the "mock-up" pictures of the adventure are arguably a bit misleading (because you aren't distributing physical copies only digital). Yes people could print it out, but unless they have a large format printer (and a long-arm stapler) and you are providing it set up to be printed double size and bound together, the "magazine style" presentation in the images is not what is described in the text.
The current form of the cover also has a general design layout that would be considered to infringe on the tradedress of Wizards of the Coast, though I believe they would permit such if you distibuted it as a DMs Guild exclusive product, and a knock-off D&D logo that would definitely run far afoul of their legal department in any context.
I recommend consulting an attorney for this project, particularly given the minefield of trademark issues surrounding the mostly-but-not-quite-in-the-public-domain Lovecraftian Mythos.
Good luck.