Just paid full price ($5.99) for this. Game says your pack is incompatible with 1.12, outdated, and crashes the game hard when I tried.
What's the problem?
Tell me about your PC specs. If your PC should be able to handle a pack like this, then you may need to allocate more RAM into Minecraft (look up tutorials). Also, if a resource pack is shown in red, that just means the mcmeta file that holds the description and stuff is not updated to format 3. So generally, if a pack claims to be outdated, it usually isn't and can be run on any version.