Capcom hired the guys that were doing the re2 remake to help with the official.
There's a very clear difference within the business strategies between those two companies, Capcom is far more lenient with its properties, so essentially anyone can make a Megaman fan game without getting a C&D order, heck, one of Capcom's "official" games is just a megaman fan game, the "Street Fighter vs Megaman" game that got its fame through the anniversary of Megaman.
While RE is a far more valuable property in terms of actual developing, writing scenario, etc. the guy who did most of the Fan remake alone worked a lot to produce wonderful results, without the need of a Kickstarter nor Outside Help, but look at this guy compared to those creators, he asks money to buy or at least get permission to use the Castlevania licensee, has no knowledge of legal terms or contracts which is something basic if you want to get money from people and then use it in the future towards the creation path of a videogame.
He only used basic models, the UI of the game looks as basic as it gets, etc. Bottom line, if you wanna make a videogame based on another company's property, read and evaluate how much lenient will the company be towards that project, and as we all know, Konami isn't an exemplar in being communicative nor open with its fans, as I stated again, my point still holds water.