ug.lyduckling

So....I installed the 1.15.2 mod before but I want to play with the decocraft mod, which is at 1.12.2 at the latest. So I want to install the 1.12.2 forge to play with decocraft(idk if that works im not good with these things, but thats just what i thought of)but everytime i try to install it, it gets stuck at the part in the screenshot and never finishes installing. I thought maybe it just took forever, but people said it installs fast, and I let it try to install overnight, and it still didnt finish. HELP!!

No like, i already installed forge for 1.15.2, but since I wanna play with decocraft, am I supposed to install the 1.12.2 forge?

I already have the 1.15.2 forge installed, and idk about the rest

oh..my bad i dont know about this stuff..but like it says its for 1.12.2 and it wont work so what do I do now?

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plz help....

I am trying to get the decocraft mod, but everytime i download it saying its for 1.15.2, I try to use it in minecraft and it shows me that its for 1.12.2...What do I do?